Mid-life vaccine and methods for boosting anti-mycobacterial immunity

ABSTRACT

Vaccine compositions for boosting immunity to mycobacteria when administered in mid-life in a subject who has been vaccinated neonatally or in early childhood with BCG and in whom protective immunity has waned comprise one or more purified immunogenic proteins from  Mycobacterium tuberculosis  from a group of 30 proteins that stimulate T cell immunity and interferon-γ secretion. A preferred protein is Ag85A, the secreted product (SEQ ID NO:31) of the Rv3084c gene. Also disclosed are methods for boosting immunity in such BCG-vaccinated subjects comprising administering an effective amount of the above vaccine composition.

This Application was filed under 35 U.S.C. § 371 based on international application Ser. No. PCT/US01/21717 (filed 10 Jul. 2001) and claims priority from U.S. Provisional Application Ser. No. 60//217,646, filed 10 Jul. 2000.

This invention was funded in part by grants AI045707, AI075320 and AG006946 from the National Institutes of Health, which provides to the United States government certain rights in this invention.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention in the fields of microbiology, immunology and medicine is directed to vaccine compositions and methods for preventing or treating mycobacterial diseases that are particularly suited to immunize a subject in mid-life who has been vaccinated neonatally or in early childhood with BCG and in whom protective immunity has waned. Thirty proteins from Mycobacterium tuberculosis are disclosed as having the desired immunogenicity and T cell stimulatory activity for such use. A preferred protein is Ag85A, the secreted product (SEQ ID NO:31) of the Rv3084c gene.

2. Description of the Background Art

Current epidemiologic data indicates that disease caused by the facultative intracellular bacterial parasite Mycobacterium tuberculosis (M. tuberculosis or “Mtb”) remains a serious global problem with around 8 million new cases per year, and with recent disturbing evidence that the death rate may be increasing (B. R. Bloom et al., Science 257:1055-64 (1992); M. C. Raviglione et al., Lancet 350:624-9 (1997); P. J. Dolin et al., Bull World Health Organ 72, 213-20 (1994); D. E. Snider, Jr., et al., N Engl J Med 338:1689-90 (1998).

For several decades the M. bovis-derived bacillus Calmette Guerin (BCG) has been the only widely used vaccine for tuberculosis (“TB”). BCG organisms, a strain of M. bovis, has been the only widely used vaccine for TB. However, accumulating data from clinical trials and subsequent meta-analysis (G. A. Colditz, et al., JAMA 271:698-702 (1994); J. A. Sterne et al., Int J Tuberc Lung Dis 2:200-7 (1998)) are revealing its general ineffectiveness in adults. It is noteworthy that adults vaccinated with BCG as young children become relatively unprotected. As a result many investigators are seeking to develop a new TB vaccine (I. M. Orme, Adv Vet Med 41:135-43 (1999); 1. M. Orme, Infect Dis Clin North Am 13:169-85, vii-viii (1999)); virtually all efforts are directed towards discovering new candidate vaccines that can be used in either or both prophylactic or immunotherapeutic modes (P. Andersen, Scand J Immunol 45:115-31 (1997). M. A. Horwitz et al., Proc Natl Acad Sci USA 92, 1530-4 (1995); D. B. Lowrie, et al., Nature 400:269-71 (1999)).

The mechanism underlying the gradual loss of effectiveness of BCG as the neonatally inoculated subject reaches 10-15 years of age is poorly understood. One possibility is that immunological memory generated by BCG has disappeared so that the subject is now the functional equivalent of a naive host that should be vaccinated with a new candidate vaccine that is designed to induce primary immunity as does BCG. An alternate possibility is slowly declining immunological memory can be re-induced by boosting with a candidate antigen that is specifically recognized by host memory cells (primarily T cells). The present invention is directed to the latter possibility and indeed discloses a number of Mtb antigens that can restimulate T cell memory and protective immunity.

The recent elucidation of the entire genome sequence of M. tuberculosis strain H37Rv (Cole, S. T. et al., Nature 1998, 393:537-544) is one of the most significant advancements to occur in tuberculosis research over the last decade and this data is now the backbone for several facets of tuberculosis research, including detailed analyses of the proteome of M. tuberculosis. Several laboratories have published two-dimensional (“2-D”) protein maps of the subcellular-fractions of M. tuberculosis (Jungblut, P R. et al., Mol. Microbiol. 1999, 33:1103-1117; Sonnenberg, M G and Belisle, J T, Infect. Immun. 1997, 65:4515-4524). Others have applied this technology to evaluate the proteins produced by Mycobacterium spp. during intracellular growth (Sturgill-Koszycki, S et al. Electrophoresis 1997, 18:2558-2565; Bai-Yu, L. et al., J. Clin. Invest. 1995, 96: 245-2496). Proteomics is also a facile approach to identifying immunodominant molecules. Through the use of 2-D PAGE and Western blot analysis, Samanich et al., J. Infect. Dis. 1998, 178, 1534-1538, recently defined 26 proteins of M. tuberculosis that reacted with antibodies of tuberculosis patients, and three of theses were determined to have potent serodiagnostic potential. See also, Laal et al., U.S. Pat. No. 6,245,331. However such an approach has not been applied on a large scale to the molecular identification of the T cell antigens of M. tuberculosis.

T cells mediate the protective immune response to an M. tuberculosis infection (Orme, I M et al., J. Infect. Dis. 1993, 167:1481-1497), and elucidation of the T cell antigens has been a driving force in the identification of M. tuberculosis proteins. However, many of the proteins assessed for T cell reactivity were selected because they were abundant, easily purified or reactive to existing monoclonal antibodies (mAbs). Realizing that the study of T cell antigens required a systematic approach, Andersen and Heron, J. Immun. Methods 1993. 16, 29-39, developed a whole-gel elutor to systematically fractionate short-term M. tuberculosis culture filtrate proteins (CFPs) by size. This group and others have used this technique to identify T cell antigens and develop 1-D patterns of proteins inducing T cell reactivity (Boesen, H et al., Infect. Immun. 1995, 63:1491-1497; Roberts, A D et al., Immunol. 1995, 85:502-508). Andersen's group (Weldingh, K et al., FEMS Immunol. Med. Microbiol. 1999, 23:159-164) recently coupled this technique with preparative IEF to provide greater resolution. However, this work was focused on characterization of a small number of proteins. Similarly, Gulle et al., Vet. Immunol. Immunopath. 1995, 48:183-190) performed T cell proliferative studies of M. bovis BCG proteins that were electroeluted from 2-D polyacrylamide gels. Although this work revealed a detailed 2-D pattern of potential T cell antigens, those proteins found to be immunogenic were not identified. Moreover this approach had several inherent limitations such as, the amount of protein obtained by elution from a single gel was insufficient for multiple analyses, and the concentration of individual proteins tested varied.

Several laboratories, including the present inventors', have shown that proteins found in Mtb culture filtrates are highly immunogenic and have promise as candidate vaccines (Orme, supra). One member of this pool, disclosed herein to be a preferred boosting antigen, is the mycolyl transferase A enzyme also termed Ag85A (J. T. Belisle, et al., Science 276:1420-2 (1997)) (and also known as FbpA, encoded by the Mtb gene Rv3804c (available in GenBank).

The present inventors and their colleagues demonstrated that the majority of CD4+ T cells accumulating in the lungs of immune mice after challenge infection recognize this antigen (A. M. Cooper et al., Tuber Lung Dis 78:67-73 (1997)).

Mice infected with M. tuberculosis generate T cells that recognize the Ag85 protein. As a consequence, investigators have attempted to use Ag85 protein as a primary vaccine. It appears that no one has shown any vaccine or antigen preparation that approaches the protection conferred by the “gold standard” vaccine, BCG.

Horwitz MA et al., 1995, supra, claimed that Ag85 protein protected guinea pigs against aerosol TB. This study was said by the authors to demonstrate that immunization with the Mtb 30-kDa major secretory protein (Ag85A), alone or in combination with other abundant extracellular Mtb proteins induced strong cell-mediated immune responses and substantial protective immunity against aerosal challenge with virulent Mtb bacilli in the highly susceptible guinea pig model of pulmonary tuberculosis. Protection was manifested by decreased morbidity (including decreased weight loss and mortality), and decreased growth of Mtb in the lungs and spleens compared with sham-immunized controls. The authors concluded that purified major extracellular proteins of Mtb are candidate components of a subunit vaccine against TB. It is noteworthy that Ag85 was given mixed with other proteins, and an adjuvant that cannot be used in humans. Moreover, the experiment had no positive control, it was halted before the negative control animals died. This paper has been widely criticized for its lack od proper scientific methodology.

In contrast, the present inventors conducted a controlled, uncontaminated test of Ag85 as a primary vaccine in guinea pigs and found no reduction in lung bacterial load.

U.S. Pat. No. 5,736,524 discloses the use of primary DNA vaccines that encode Ag85. However, experience since this document became public has shown that the vaccines disclosed therein are even less effective than BCG.

Moreover, booster inoculation of BCG has proven ineffective. Thus, people who were neonatally vaccinated with BCG are at risk for TB as their T cell reactivity and antibody titers decline over time after primary vaccination.

While there is a desperate need to develop new TB vaccines to deal with the global emergency in general, in more advanced countries TB continues to be relatively more common in the elderly (W. W. Stead et al., Annu Rev Med 42: 267-726 (1991); W. W. Stead, Int J Tuberc Lung Dis 2: S64-70 (1998)). In the United States, for instance, people over the age of 65 have for some time now represented the fastest growing segment of the overall population (US Census Bureau. Worldwide Web page having the URL:.census.gov/socdemo/www/agebrief.html). While primary TB sometimes occurs in these individuals, the majority of cases are thought to be due to reactivation of latent disease acquired many decades earlier (Steadl, 1998, supra). h view of this, the vaccine strategy disclosed herein is applicable for preventing reactivation TB in the elderly.

Citation of the above documents is not intended as an admission that any of the foregoing is pertinent prior art. All statements as to the date or representation as to the contents of these documents is based on the information available to the applicant and does not constitute any admission as to the correctness of the dates or contents of these documents.

SUMMARY OF THE INVENTION

The present inventors have discovered, through the use of 2-D liquid phase electrophoresis (LPE) (Davidsson, P et al., Biochim. Biophys. Acta 1999, 1473:391-399) coupled with an in vitro interferon-γ (IFNγ) assay (Orme, IM et al., J. Immunol. 1993,151:518-52516), and liquid chromatograph-mass spectromeltry (LC-MS) T cell immunogens in the culture filtrate and cytosol fractions of M. tuberculosis. In total, 31 individual proteins that stimulated a strong IFNγ response from T cells of M. tuberculosis infected mice were identified. This procedure permitted recovery of significant total amounts olf proteins and had the advantage of rapidly and accurately identifying the proteins that can serve as T cell immunogens. See, also: Covert, B A et al., Proteomics, 2001, 1:574-586, which is incorporated by reference in its entirety.

The present inventors discovered that immunization with an immunogenic secreted protein of Mtb, as exemplified by Ag85A, boosted the immune response, and thus the state of existing immunological memory, in recipients that had been previously vaccinated with BCG See, also: Brooks, J. V. et al., Infec. Immun., 2001, 69:2714-2717, which is incorporated by reference in its entirety.

Studies performed in mice showed that midlife boosting of BCG-vaccinated animals restored resistance to challenge with virulent M. tuberculosis organisms when the subjects were elderly. Such a state of resistance was not seen in animals that had simply been given BCG early in life.

The present invention provides a vaccine composition useful for boosting the immune response to Mtb in a mammal which has been vaccinated neonatally or early in life with BCG, to increase the resistance of the mammal to Mtb infection, the composition comprising one or more, (or, in another embodiment, two or more, or in yet another embodiment, three or more) purified Mtb proteins, or homologues or functional derivatives of the proteins, which protein, homologue or functional derivative is characterized in that that it:

-   (a) stimulates significant interferon-γ secretion by T lymphocytes     of a mammal which has been immunized with Mtb antigens; and/or -   (b) when administered to a mammalian subject at an age when immunity     induced by the BCG vaccination is waning, it significantly increases     the resistance of the subject to Mtb infection.

Preferably in the above vaccine composition, the purified Mtb proteins are selected from the group consisting of the product of the Mtb gene Rv3804c, Rv1886c, Rv0029c, Rv1860, Rv0934, Rv0577, Rv1827, Rv3841, Rv1932, Rv1352, Rv3418c, Rv3875, Rv1810, Rv1980c, Rv0350, Rv3044, Rv0054, Rv0652, Rv3029c, Rv3028c, Rv2428, Rv0440, Rv2031c, Rv2626c, Rv1211, Rv1240, Rv1626, Rv0733, Rv2461c, and Rv0952.

Alternatively, in the vaccine composition, the purified proteins are selected from the group consisting of SEQ ID NO:1, SEQ: ID NO:2, SEQ: ID NO:3, SEQ: ID NO:4, SEQ: ID NO:5, SEQ: ID NO:6, SEQ: ID NO:7, SEQ: ID NO:8, SEQ: ID NO:9, SEQ ID NO:10, SEQ ID NO:11, SEQ ID NO:12, SEQ ID NO:13, SEQ ID NO:14, SEQ ID NO:15, SEQ ID NO:16, SEQ ID NO:17, SEQ ID NO:18, SEQ ID NO:19, SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, SEQ ID NO:24, SEQ ID NO:25, SEQ ID NO:26, SEQ ID NO:27, SEQ ID NO:28, SEQ ID NO:29, SEQ ID NO:30 and SEQ ID NO:31, wherein, when the protein is an Mtb secreted protein, the sequence is the truncated sequence of the above sequences from which the signal sequence has been removed.

In another embodiment of the vaccine composition, the proteins are selected from the group consisting of SEQ ID NO:6; SEQ ID NO:8; SEQ ID NO:10; SEQ ID NO:13; SEQ ID NO:16; SEQ ID NO:17; SEQ ID NO:18; SEQ ID NO:19; SEQ ID NO:20; SEQ ID NO:21; SEQ ID NO:24; SEQ ID NO:25; SEQ ID NO:26; SEQ ID NO:27; SEQ ID NO:28; SEQ ID NO:29 and SEQ ID NO:30.

In yet another embodiment of the vaccine composition, the proteins are selected from the group consisting of SEQ ID NO:6; SEQ ID NO:7; SEQ ID NO:10; SEQ ID NO:13; SEQ ID NO:24; SEQ ID NO:25 and SEQ ID NO:27.

A preferred vaccine composition includes Ag85A (SEQ ID NO:31).

The above vaccine composition preferably further comprises an adjuvant or an immunostimulatory protein different from the immunogenic Mtb proteins. The immunostimulatory protein may be a cytokine, e.g., interleukin 2 or GM-CSF.

The adjuvant is preferably one or more of: (a) ISAF-1 (5% squalene, 2.5% pluronic L121, 0.2% Tween 80) in phosphate-buffered solution with 0.4 mg of threonyl-muramyl dipeptide; (b) Amphigen®; (c) Alhydrogel®; (d) a mixture of Amphigen® and Alhydrogel® (e) QS-21; and (f) monophosphoryl lipid A adjuvant. A preferred adjuvant is monophosphoryl lipid A adjuvant solubilized in 0.02% triethanolamine and a preferred cytokine is rIL-2.

Also provided herein is a method for boosting the immune response to Mycobacterium tuberculosis (Mtb) in a mammal which has been vaccinated neonatally or early in life with BCG, to increase the resistance of the mammal to Mtb infection, the method comprising administering to a mammal in need of the boosting, an immunogenically effective amount of an Mtb immunogenic protein vaccine composition as described above.

Preferably the mammal is a human. The administering is preferably performed between about 1 and about 10 years after the BCG vaccination. In preferred embodiments, the administering is performed when the human is at least about 10 years of age, or at least about 15 years of age, or at least about 20 years of age.

In one embodiment of the above method, the vaccine composition includes a single Mtb protein (or homologue or functional derivative thereof. A preferred protein is Ag85A (SEQ ID NO:31).

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-4 show IFNγ responses of spleen lymphocytes harvested from C57B1/6 mice at 10 days (FIGS. 1 and 2) and 40 days (FIGS. 3 and 4) post infection with M. tuberculosis H37Rv. FIGS. 1 and 3 show responses to the 2-D LPE fractions of the CFPs, and FIGS. 2 and 4 are the responses to the 2-D LPE. fractions of the cytosolic proteins. Each bar represents a T cell response to a single 2-D LPE fraction. These responses were calculated as the amount (ng/mL) of IFN-γ produced by cells from infected mice minus the IFNγ produced by cells from uninfected mice tested with the same 2-D LPE fraction. Each vertical data bar progressing in a row along the “kDa” axis (some showing different hatching patterns), represents a molecular weight range of 5 kDa. All 2-D LPE fractions were placed in a molecular weight range of 10-15, 15-20, 20-25, 25-30, 30-35, 35-40, 40-45, 45-45, 50-55, 55-60, 60-65, 65-70, 70-75, 75-80, 80-85, 85-90, 90-95, 95-100, 100-105, 105-110, 110-115, or 115-120 kDa.

FIG. 5 is a graph showing that the protective effect of BCG gradually wanes as animals grow older. C57B1/6 mice were vaccinated subcutaneously with 10⁶ M. bovis BCG strain Pasteur at 6 weeks of age and challenged at the indicated time points by exposure to an aerosol delivered infection of approximately 50 bacteria of M. tuberculosis H37Rv. Mice were euthanized thirty days later and bacterial counts in the lungs determined by plating on Middlebrook 7H11 agar. Levels of protection to the challenge were determined by calculating mean values (log₁₀) of 4-5 mice and subtraction from values obtained in unvaccinated, age-matched controls.

FIG. 6 is a graph showing that vaccination of 20 month old mice with a culture filtrate protein (CFP) vaccine resulted in only a marginal reduction in the lung bacterial load after aerosol challenge (as in FIG. 5). Mice were vaccinated twice, three weeks apart, and then rested four weeks before aerosol infection. The vaccine consisted of 100 μg purified mid-log phase CFPs from M. tuberculosis H37Rv emulsified in monophosphoryl lipid A adjuvant solubilized in 0.02% triethanolamine plus 100 μg rIL-2 cytokine. Bacterial counts were determined as above thirty days after challenge.

FIG. 7 shows an SDS-PAGE gel of enriched Mtb culture filtrate proteins (lane B) and purified Ag85A (lane C). Lane A has molecular weight markers.

FIG. 8 is a graph showing that vaccination followed by boosting with Ag85A improves resistance to aerosol challenge compared to BCG vaccination alone. Mice were inoculated with BCG as above at 8 weeks of age; controls were injected with saline. At 9 and 15 months of age, they were boosted with either CFP or Ag85A in an adjuvant vehicle (monophosphoryl Lipid A/rIL-2). Mice were challenged by aerosol at 20 months of age. Only the Ag85A-treated group showed a statistically significant diminution of lung bacterial counts relative to the saline controls (p<0.001).

FIG. 9 presents a set of representative photomicrographs of lung tissue from vaccine boosted mice following aerosol infection with M. tuberculosis. All plates were stained with hematoxylin and eosin, and all size bars represent 10 μm.

-   Plate A: Lung adjacent to a bronchiole (arrowhead) from a mouse from     the BCG vaccination group. Alveolar septa containing epithelioid     macrophages and infiltrates of neutrophils, often forming small     aggregates, were evident (arrows). -   Plate B: Lung adjacent to a bronchiole (arrowhead) from a mouse from     the BCG/Ag85 vaccination group. The alveolar septa showed influx by     epithelioid macrophages, whereas neutrophils were scattered and rare     (arrows). -   Plate C: Higher magnification of lung from a mouse from the BCG     vaccination group. Arrows depict an aggregate or pocket of     neutrophils within an alveolar septum. -   Plate D: Higher magnification of lung from a mouse from the BCG/Ag85     vaccination group. The septa were thickened by an influx of     macrophages. Neutrophils were rare; the arrow indicates an solitary     neutrophil.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

This invention represents the first discovery an animal immunized when young with BCG can be boosted in mid-life with an antigen that is strongly recognized by the memory T lymphocytes, resulting in the expression of immunity in the elderly animal that is equivalent in potency to that seen in young mice vaccinated with BCG (and challenged soon thereafter).

While these observations were in mice, the present invention provides compositions and methods to achieve a similar effect in humans that had been previously vaccinated with BCG.

Another advantage of the present approach is considerable simplification of testing new vaccines in the field, particularly in the third world. Although most vaccine research focuses on new prophylactic measures to replace BCG vaccination altogether, the fact remains that most newborn children, especially in regions where TB is prevalent, are given BCG vaccination almost immediately after birth.

In fact it is not known if most vaccine strategies under development will actually work if given to people who haw: an existing state of immunity, measured in any of a number of ways, to Mtb.

The present approach offers the advantage that it does not ignore the fact of previous BCG vaccination like the approaches of others that attempt to design vaccines to induce a “new” state of primary immunity. Rather, the present invention is specifically targeted to subjects who carry a state of immunological memory by using any one or a combination of purified protein antigens (or immunogenic epitopes thereof) that are recognized by T cells, preferably, CD4+ memory T cells, even if these T cells exist in a milieu (or pool) or memory cells that is gradually waning over time. As described in Example I, below, Ag85A is a preferred example of such an antigen.

The present invention is superior to the strategy of using an immunogenic protein or proteins, such as Ag85A, directly as a primary vaccine. It has been shown that some degree of primary immunity can certainly be generated against such proteins, e.g., Ag85, ESAT-6, 45 kDa, etc., in mice (I. M. Orme, Infect Dis Clin North Am 13, 169-85, vii-viii (1999); S. H. Kaufmann et al., Chem Immunol 70:21-59 (1998)). However, such a level of immunity does not usually exceed that conferred by BCG, and more importantly, there is no evidence to date of a sustained, long-lived state of immunological memory established by primary immunization with individual proteins or mixtures of such proteins.

The present inventors and their colleagues have found that immunization with Ag85A can induce modest levels of protection in mice challenged 30 days later (S. L. Baldwin, et al., Infect Immun 66:2951-2959 (1998)). In guinea pigs, such immunization had no effect on the bacterial load, although modest “clinical” benefits, measured as lymphocytic granuloma formation in lungs coupled with reasonably long term survival were observed (unpublished observations). This however did not compare to BCG vaccination, which resulted in 2-3 log reduction in a bacterial load and animals living for most of their expected lifespan. A much better single protein immunization result was obtained if the Ag85A was delivered in the form of a DNA vaccine (K. Huygen et al., Nature Med 8: 893-898 (1996)). Again, however, this strategy did not appreciably reduce the bacterial load in the sensitive guinea pig model.

It is unknown why Ag85A cannot prime animals to the degree achieved by BCG. This underscores the current inability in the art to induce a strong T_(H)1-mediated primary and long-lived memory response to non-living vaccines compared to levels attained using BCG.

One limitation is the paucity of vaccine adjuvants. The present inventors and others have worked with relatively mild adjuvants such as monophosphoryl lipid A (MPL) and DDA primarily because they are considered safe for use in humans. However, these adjuvants alone are believed to be insufficient to induce long lived T_(H)1-mediated immunity. However, according to the present invention, such adjuvants are sufficiently effective for boosting of a response in a BCG-vaccinated subject using an isolated protein antigen (or mixture thereof) when the subject already has sufficient antigen-specific T_(H)1 cells; as part of a state of specific immunological memory as a result of BCG exposure early in life.

Recombinant M. Tuberculosis Proteins

Purified immunogenic Mtb proteins described herein may be produced using recombinant methods. Conventional bacterial expression systems utilize Gram negative bacteria such as E. coli or Salmonella species. However, it is believed that such systems may not be ideally suited for production of Mtb antigens (Burlein, J. E., In: Tuberculosis: Pathogenesis, Protection and Control, B. Bloom, ed., Amer. Soc. Microbiol., Washington, D.C., 1994, pp. 239-252). Rather, it is preferred to utilize homologous mycobacterial hosts for recombinant production of Mtb antigenic proteins or glycoproteins. Methods for such manipulation and gene expression are provided in Burlein, supra. Expression in mycobacterial hosts, in particular M. bovis (strain BCG) or M. smegmatis are well-known in the art. Two examples, one of mycobacterial genes (Rouse, D. A. et al., 1996, Mol. Microbiol. 22:583-592) and the other of non mycobacterial genes, such as HIV-1 genes (Winter, N. et al., 1992, Vaccines 92, Cold Spring Harbor Press, pp. 373-378) expressed in mycobacterial hosts are cited herein as an example of the state of the art. The foregoing three references are hereby incorporated by reference in their entirety.

General Recombinant DNA Methods

Basic texts disclosing general methods of molecular biology, all of which are incorporated by reference, include: Sambrook, J. et al., Molecular Cloning: A Laboratory Manual, 2^(nd) Edition, Cold Spring Harbor Press, Cold Spring Harbor, N.Y., 1989; Ausubel, F. M. et al. Current Protocols in Molecular Biology, Vol. 2, Wiley-Interscience, New York, (current edition); Kriegler, Gene Transfer and Expression: A Laboratory Manual (1990); Glover, D. M., ed, DNA Cloning: A Practical Approach, vol. I & II, IRL Press, 1985; Albers, B. et al., Molecular Biology of the Cell, 2^(nd) Ed., Garland Publishing, Inc., New York, N.Y. (1989); Watson, J. D. et al., Recombinant DNA, 2^(nd) Ed., Scientific American Books, New York, 1992; and Old, R W et al., Principles of Gene Manipulatxion: An Introduction to Genetic Engineering, 2^(nd) Ed., University of California Press, Berkeley, Calif. (1981).

Unless otherwise indicated, a particular nucleic acid sequence additionally encompasses conservative substitution variants thereof (e.g., degenerate codon substitutions) and a complementary sequence. The term “nucleic acid” is synonymous with “polynucleotide” and is intended to include a gene, cDNA molecule, an mRNA molecule, as well as a fragment of any of these such as an oligonucleotide, and further, equivalents thereof (explained more fully below). Sizes of nucleic acids stated either as kilobases (kb) or base pairs (bp) are estimates derived from agarose or polyacrylamide gel electrophoresis (PAGE), from nucleic acid sequences which are determined by the user or published. Protein size is stated as molecular mass in kilodaltons (kDa) or as length (number of amino acid residues). Protein size is estimated from PAGE, from sequencing, from presumptive amino acid sequences based on the coding nucleic acid sequence or from published amino acid sequences.

cDNA molecules encoding the amino acid sequence of the immunogenic Mtb protein or fragments or derivatives thereof can be synthesized by the polymerase chain reaction (PCR) (see, for example, U.S. Pat. No. 4,683,202) using primers derived the sequence of the protein which are publicly disclosed. These cDNA sequences can then be assembled into a prokaryotic expression vector and the resulting vector can be used to direct the synthesis of the polypeptide or its fragment or derivative by appropriate host cells as indicated above.

Fragment of Nucleic Acid

A fragment of the nucleic acid sequence is defined as a nucleotide sequence having fewer nucleotides than the nucleotide sequence encoding the full length immunogenic Mtb protein. This invention includes such nucleic acid fragments that encode polypeptides which retain: (1) the ability of immunogenic Mtb protein to bind to be taken up by host antigen presenting cells and be presented to T cells, preferably TH1 cells, specific for an epitope of that protein. This can be measured by an appropriate in vitro assay such as T cell proliferation or cytokine production, e.g., IFNγ; and (2) to enhance a T cell mediated memory response to Mtb that results in statistically significantly increased protection again bacterial growth in vivo.

Generally, the nucleic acid sequence encoding an immunogenic fragment of the Mtb protein comprises nucleotides horn the sequence encoding the mature protein. Nucleic acid sequences of this invention may also include linker sequences, natural or modified restriction endonuclease sites and other sequences that are useful for manipulations related to cloning, expression or purification of encoded protein or fragments. These and other modifications of nucleic acid sequences are described herein or are well-known in the art.

A culture typically includes bacterial cells such as mycobacteria, appropriate growth media and other byproducts. Suitable culture media are well known in the art and exemplified herein. The immunogenic Mtb protein can be isolated from the medium (or from cell lysates) using conventional techniques for purifying proteins and peptides, including ammonium sulfate precipitation, fractionation column chromatography (e.g., ion exchange, gel filtration, affinity chromatography, etc.) and/or electrophoresis (see generally, “Enzyme Purification and Related Techniques”, Methods in Enzymology, 22: 233-577 (1971)). Once purified, partially or to homogeneity, the recombinant proteins of the invention can be utilized in vaccine composition as described in more detail herein.

Vector Construction

Construction of suitable vectors containing the desired coding and control sequences employs standard ligation and restriction techniques which are well understood in the art. Isolated plasmids, DNA sequences, or synthesized oligonucleotides are cleaved, tailored, and religated in the form desired.

The DNA sequences which form the vectors are available from a number of sources. Backbone vectors and control systems are generally found on available “host” vectors which are used for the bulk of the sequences in construction. It may be possible to synthesize the entire gene sequence in vitro starting from the individual nucleotide derivatives. The entire gene sequence for genes of sizeable length, e.g., 500-1000 bp may be prepared by synthesizing individual overlapping complementary oligonucleotides and filling in single stranded nonoverlapping portions using DNA polymerase in the presence of the deoxyribonucleotide triphosphates. This approach has been used successfully in the construction of several genes of known sequence. See, for example, Edge, M. D., Nature (1981) 292:756; Nambair, K. P., et al., Science (1984) 223:1299; and Jay, E., J Biol Chem (1984) 259:6311.

Once the components of the desired vectors are thus available, they can be excised and ligated using standard restriction and ligation procedures. Site-specific DNA cleavage is performed by treating with the suitable restriction enzyme (or, enzymes) under conditions which are generally understood in the art, and the particulars of which are specified by the manufacturer of these commercially available restriction enzymes. See, e.g., New England Biolabs, Product Catalog. In general, about 1 mg of plasmid or DNA sequence is cleaved by one unit of enzyme in about 20 ml of buffer solution; in the examples herein, typically, an excess of restriction enzyme is used to insure complete digestion of the DNA substrate. Incubation times of about one hour to two hours at about 37° C. are workable, although variations can be tolerated. After each incubation, protein is removed by extraction with phenol/chloroform, and may be followed by ether extraction, and the nucleic acid recovered from aqueous fractions by precipitation with ethanol. If desired, size separation of the cleaved fragments may be performed by polyacrylamide gel or agarose gel electrophoresis using standard techniques. A general description of size separations is found in Methods in Enzymology (1980) 65:499-560.

Restriction cleaved fragments may be blunt ended by treating with the large fragment of E. coli DNA polymerase I (Klenow) in the presence of the four deoxynucleotide triphosphates (dNTPs) using incubation times of about 15 to 25 min at 20° to 25° C. in 50 mM Tris pH 7.6, 50 mM NaCl, 6 mM MgCl₂, 6 mM DTT and 0.1-1.0 mM dNTPs. The Klenow fragment fills in at 5′ single-stranded overhangs but chews back protruding 3′ single strands, even though the four dNTPs are present. If desired, selective repair can be performed by supplying only one of the, or selected, dNTPs within the limitations dictated by the nature of the overhang. After treatment with Klenow, the mixture is extracted with phenol/chloroform and ethanol precipitated. Treatment under appropriate conditions with S1 nuclease or BAL-31 results in hydrolysis of any single-stranded portion.

Ligations are typically performed in 15-50 ml volumes under the following standard conditions and temperatures: for example, 20 mM Tris-HCl pH 7.5, 10 mMMgCl₂, 10 mM DTT, 33 μg/ml BSA, 10-50 mM NaCl, and either 40 μM ATP, 0.01-0.02 (Weiss) units T4 DNA ligase at 0° C. (for “sticky end” ligation) or 1 mM ATP, 0.3-0.6 (Weiss) units T4 DNA ligase at 14° C. (for “blunt end” ligation). Intermolecular “sticky end” ligations are usually performed at 33-100 μg/ml total DNA concentrations (5-100 nM total end concentration). Intermolecular blunt end ligations are performed at 1 mM total ends concentration.

In vector construction employing “vector fragments”, the fragment is commonly treated with bacterial alkaline phosphatase (BAP) or calf intestinal alkaline phosphatase (CLAP) in order to remove the 5′ phosphate and prevent self-ligation. Digestions are conducted at pH 8 in approximately 10 mM Tris-HCl, 1 mM EDTA using BAP or CIAP at about 1 unit/mg vector at 600 for about one hour. The preparation is extracted with phenol/chloroform and ethanol precipitated. Alternatively, re-ligation can be prevented in vectors which have been double digested by additional restriction enzyme and separation of the unwanted fragments.

Promoters

A promoter region of a DNA or RNA molecule binds RNA polymerase and promotes the transcription of an “operably linked” nucleic acid sequence. As used herein, a “promoter sequence” is the sequence of the promoter which is found on that strand of the DNA or RNA which is transcribed by the RNA polymerase. Two sequences of a nucleic acid molecule, such as a promoter and a coding sequence, are “operably linked” when they are linked to each other in a manner which either permits both sequences to be transcribed onto the same RNA transcript, or permits an RNA transcript, begun in one sequence to be extended into the second sequence. Thus, two sequences, such as a promoter sequence and a coding sequence of DNA or RNA are operably linked if transcription commencing in the promoter sequence will produce an RNA transcript of the operably linked coding sequence. In order to be “operably linked” it is not necessary that two sequences be immediately adjacent to one another.

The promoter sequences of the present invention is preferably prokaryotic. Suitable promoters are repressible, or, more preferably, constitutive. Examples of suitable prokaryotic promoters include promoters capable of recognizing the T4 (Malik, S. et al., J. Biol. Chem. 263:1174-1181 (1984); Rosenberg, A. H. et al., Gene 59:191-200 (1987); Shinedling, S. et al., J. Molec. Biol. 195:471-480 (1987); Hu, M. et al., Gene 42:21-30 (1986)), T3, Sp6, and T7 (Chamberlin, M. et al., Nature 228:227-231 (1970); Bailey, J. N. et al., Proc. Natl. Acad. Sci. (U.S.A) 80:2814-2818 (1983); Davanloo, P. et al., Proc. Natl. Acad. Sci. (U.S.A.) 81:2035-2039 (1984)) polymerases; the P_(R) and P_(L) promoters of bacteriophage λ (The Bacteriophage Lambda, Hershey, A. D., Ed., Cold Spring Harbor Press, Cold Spring Harbor, N.Y. (1973); Lambda II, Hendrix, R. W., Ed., Cold Spring Harbor Press, Cold Spring Harbor, N.Y. (1980)); the trp, recA, heat shock, and lacZ promoters of E. coli; the α-amylase (Ulmanen, I., et al., J. Bacteriol. 162:176-182 (1985)) and the σ-28-specific promoters of B. subtilis (Gilman, M. Z., et al., Gene 32:11-20 (1984)); the promoters of the bacteriophages of Bacillus (Gryczan, T. J., In: The Molecular Biology of the Bacilli, Academic Press, Inc., NY (1982)); Streptomyces promoters (Ward, J. M., et al., Mol. Gen. Genet. 203:468-478 (1986)); the int promoter of bacteriophage λ; the bla promoter of the β-lactamase gene of pBR322, and the CAT promoter of the chloramphenicol acetyl transferase gene of pPR325, etc. Prokaryotic promoters are reviewed by Glick, B. R. (J. Ind. Microbiol. 1:277-282 (1987)); Cenatiempo, Y. (Biochimie 68:505-516 (1986)); Gottesman, S. (Ann. Rev. Genet. 18:415-442 (1984) and the general references cited above. All of the above listed references are incorporated by reference herein. Strong promoters are preferred. Examples of such preferred promoters are those which recognize the T3, SP6 and T7 polymerases, the P_(L) promoter of bacteriophage λ, the recA promoter

The nucleic acid sequences of the invention can also be chemically synthesized using standard techniques. Various methods of chemically synthesizing polydeoxynucleotides are known, including solid-phase synthesis which, like peptide synthesis, has been fully automated with commercially available DNA synthesizers (See e.g., Itakura et al. U.S. Pat. No. 4,598,049; Caruthers et al. U.S. Pat. No. 4,458,066; and Itakura U.S. Pat. Nos. 4,401,796 and 4,373,071, incorporated by reference herein).

Proteins and Polypeptides

The present invention includes an “isolated” immunogenic Mtb protein. Preferably, the protein is selected from the following proteins shown in Tables 1 and 2, below (SEQ ID NO:1-SEQ ID NO:30.

A most preferred protein is Ag85A, a protein having 295 amino acids which is the secreted form of SEQ ID NO:1 and which has the sequence:

FSRPGLPVEY LQVPSPSMGR DIKVQFQSGG ANSPALYLLD GLRAQDDFSG (SEQ ID NO: 31) WDINTPAFEW YDQSGLSVVM PVGGQSSFYS DWYQPACGKA GCQTYKWETF LTSELPGWLQ ANRHVKPTGS AVVGLSMAAS SALTLAIYHP QQFVYAGAMS GLLDPSQAMG PTLIGLAMGD AGGYKASDMW GPKEDPAWQR NDPLLNVGKL IANNTRVWVY CGNGKPSDLG GNNLPAKFLE GFVRTSNIKF QDAYNAGGGH NGVFDFPDSG THSWEYWGAQ LNAMKPDLQR ALGATPNTGP APQGA.

Also preferred as vaccine compositions are mixtures of two of more purified proteins listed in the Table 1 and 2. A more preferred mixture includes Ag85A (SEQ ID NO:31).

While full length native immunogenic Mtb proteins are described, it is to be understood that use of homologues of these proteins from other mycobacterial species and mutants thereof that possess the characteristics disclosed herein are intended within the scope of this invention.

Also included is a “functional derivative” of the immunogenic Mtb protein which includes amino acid substitution “variants,” “fragments” or a “chemical derivatives” of the immunogenic Mtb protein which terms are defined below. A functional derivative retains measurable activity, preferably that of stimulating T_(H)1 cells, preferably those from a subject primed by earlier BCG vaccination, to proliferate or to secrete cytokines. Assays for T_(H)1 cytokines, preferably interferon-γ (IFNγ) (see Example I et seq.). IL-12 and IL-18 are well-known in the art and can be performed by peripheral blood T lymphocytes obtained from a subject, before, during a course of, or at various times after, booster immunization. Thus, one way to predict whether a protein, fragment or other functional derivative falls within the scope of the present claims is to test the ability of the protein, fragment or derivative to induce IFNγ production by T cells from Mtb-immunized donors, preferably human donors, most preferably having the same major histocompatibility complex (MHC) phenotype as the subject to be immunized or the prospective recipient himself. In addition to the assays described in Example I, other well-known assays for IFNγ, including Elispot assays that permit enumeration of IFNγ-secreting cells may be used.

TABLE 1 Immunodominant Secreted Mtb Proteins identified in CFP^(a) H37Rv Common Gene Names SEQ Product (length - aa) ID NO: Amino Acid Sequences^(c) Rv3804c FbpA 1 MQLVDRVRGA VTGMSRRLVV GAVGAALVSG LVGAVGGTAT AGA FSRPGLP Ag85A VEYLQVPSPS MGRDIKVQFQ SGGANSPALY LLDGLRAQDD FSGWDINTPA 338 aa FEWYDQSGLS VVMPVGGQSS FYSDWYQPAC GKAGCQTYKW ETFLTSELPG WLQANRHVKP TGSAVVGLSM AASSALTLAI YHPQQFVYAG AMSGLLDPSQ AMGPTLIGLA MGDAGGYKAS DMWGPKEDPA WQRNDPLLNV GKLIANNTRV WVYCGNGKPS DLGGNNLPAK FLEGFVRTSN IKFQDAYNAG GGHNGVFDFP DSGTHSWEYW GAQLNAMKPD LQRALGATPN TGPAPQGA Rv1886c FbpB 2 MTDVSRKIRA WGRRLMIGTA AAVVLPGLVG LAGGAATAGA FSRPGLPVEY Ag85B LQVPSPSMGR DIKVQFQSGG NNSPAVYLLD GLRAQDDYNG WDINTPAFEW 325 aa YYQSGLSIVM PVGGQSSFYS DWYSPACGKA GCQTYKWETF LTSELPQWLS ANRAVKPTGS AAIGLSMAGS SAMILAAYHP QQFIYAGSLS ALLDPSQGMG PSLIGLAMGD AGGYKAADMW GPSSDPAWER NDPTQQIPKL VANNTRLWVY CGNGTPNELG GANIPAEFLE NFVRSSNLKF QDAYNAAGGH NAVFNFPPNG THSWEYWGAQ LNAMKGDLQS SLGAG Rv0129c FbpC2 3 MTFFEQVRRL RSAATTLPRR LAIAAMGAVL VYGLVGTFGG PATAGA FSRP Ag85C GLPVEYLQVP SASMGRDIKV QFQGGGPHAV YLLDGLRAQD DYNGWDINTP 340 aa AFEEYYQSGL SVIMPVGGQS SFYTDWYQPS QSNGQNYTYK WETFLTREMP AWLQANKGVS PTGNAAVGLS MSGGSALILA AYYPQQFPYA ASLSGFLNPS EGWWPTLIGL AMNDSGGYNA NSMWGPSSDP AWKRNDPMVQ IPRLVANNTR IWVYCGNGTP SDLGGDNIPA KFLEGLTLRT NQTFRDTYAA DGGRNGVFNF PPNGTHSWPY WNEQLVAMKA DIQHVLNGAT PPAAPAAPAA Rv1860 ModD 4 MHQVDPNLTR RKGRLAALAI AAMASASLVT VAVPATANA D PEPAPPVPTT MPT32 AASPPSTAAA PPAPATPVAP PPPAAANTPN AQPGDPNAAP PPADPNAPPP 325 aa PVIAPNAPQP VRIDNPVGGF SFALPAGWVE SDAAHFDYGS ALLSKTTGDP PFPGQPPPVA NDTRIVLGRL DQKLYASAEA TDSKAAARLG SDMGEFYMPY PGTRINQETV SLDANGVSGS ASYYEVKFSD PSKPNGQIWT GVIGSPAANA PDAGPPQRWF VVWLGTANNP VDKGAAKALA ESIRPLVAPP PAPAPAPAEP APAPAPAGEV APTPTTPTPQ RTLPA Rv0934 PhoS1 5 VKIRLHTLLA VLTAAPLLLA AAG CGSKPPS GSPETGAGAG TVATTPASSP PstS1 VTLAETGSTL LYPLFNLWGP AFHERYPNVT ITAQGTGSGA GIAQAAAGTV 374 aa NIGASDAYLS EGDMAAHKGL MNIALAISAQ QVNYNLPGVS EHLKLNGKVL AAMYQGTIKT WDDPQIAALN PGVNLPGTAV VPLHRSDGSG DTFLFTQYLS KQDPEGWGKS PGFGTTVDFP AVPGALGENG NGGMVTGCAE TPGCVAYIGI SFLOQASQRG LGEAQLGNSS GNFLLPDAQS IQAAAAGFAS KTPANQAISM IDGPAPDGYP IINYEYAIVN NRQKDAATAQ TLQAFLHWAI TDGNKASFLD QVHFQPLPPA VVKLSDALIA TISS Rv0577 None^(d) 6 MPKRSEYRQG TPNWVDLQTT DQSAAKKFYT SLFGWGYDDN PVPGGGGVYS 261 aa MATLNGEAVA AIAPMPPGAP EGMPPIWNTY IAVDDVDAVV DKVVPGGGQV MMPAFDIGDA GRMSFITDPT GAAVGLWQAN RHIGATLVNE TGTLIWNELL TDKPDLALAF YEAVVGLTHS SMEIAAGQNY RVLKAGDAEV GGCMEPPMPG VPNHWHVYFA VDDADATAAK AAAAGGQVIA EPADIPSVGR FAVLSDPQGA IFSVLKPAPQ Q Rv1827 CP17 7 VTDMNPDIEK DQTSDEVTVE TTSVFRADFL SELDAPAQAG TESAVSGVEG 162 aa LPPGSALLVV KRGPNAGSRF LLDQAITSAG RHPDSDIFLD DVTVSRRHAE FRLENNEFNV VDVGSLNGTY VNREPVDSAV LANGDEVQIG KFRLVFLTGP KQGEDDGSTG GP Rv3841 BfrB 8 MTEYEGPKTK FHALMQEQIH NEFTAAQQYV AIAVYFDSED LPQLAKHFYS 181 aa QAVEERNHAM MLVQHLLDRD LRVEIPGVDT VRNQFDRPRE ALALALDQER TVTDQVGRLT AVARDEGDFL GEQFMQWFLQ EQIEEVALMA TLVRVADRAG ANLFELENFV AREVDVAPAA SGAPHAAGGR L Rv1932 Tpx 9 MAQITLRGNA INTVGELPAV GSPAPAFTLT GGDLGVISSD QFRGKSVLLN 165 aa IFPSVDTPVC ATSVRTFDER AAASGATVLC VSKDLPFAQK RFCGAEGTEN VMPASAFRDS FGEDYGVTIA DGPMAGLLAR AIVVIGADGN VAYTELVPEI AQEPNYEAAL AALGA Rv1352 None^(d) 10 MARTLALRAS AGLVAGMAMA AITLAPGARA ETGEQFPGDG VFLVGTDIAP 123 aa GTYRTEGPSN PLILVFGRVS ELSTCSWSTH SAPEVSNENI VDTNTSMGPM SVVIPPTVAA FQTHNCKLWM RIS Rv3418c GroES 11 VAKVNIKPLE DKILVQANEA ETTTASGLVI PDTAKEKPQE GTVVAVGPGR 100 aa WDEDGEKRIP LDVAEGDTVI YSKYGGTEIK YNGEEYLILS ARDVLAVVSK Rv3875 ESAT6 12 MTEQQWNFAG IEAAASAIQG NVTSIHSLLD EGKQSLTKLA AAWGGSGSEA 95 aa YQGVQQKWDA TATELNNALQ NLARTISEAG QAMASTEGNV TGMFA Rv1810 None^(d) 13 MQLQRTMGQC RPMRMLVALL LSAATMIGLA APGKADPTGD DAAFLAALDQ 118 aa AGITYADPGH AITAAKAMCG LCANGVTGLQ LVADLRDYNP GLTMDSAAKF AAIASGAYCP EHLEHHPS Rv1980c MPT64 14 VRIKIFMLVT AVVLLCCSGV ATA APKTYCE ELKGTDTGQA CQIQMSDPAY 228 aa NINISLPSYY PDQKSLENYI AQTRDKFLSA ATSSTPREAP YELNITSATY QSAIPPRGTQ AVVLKVYQNA GGTHPTTTYK AFOWOQAYRK PITYDTLWQA DTDPLPVVFP IVQGELSKQT GQQVSIAPNA GLDPVNYQNF AVTNDGVIFF FNPGELLPEA AGPTQVLVPR SAIDSMLA Rv0350 DnaK 15 MARAVGIDLG TTNSVVSVLE GGDPVVVANS EGSRTTPSIV AFARNGEVLV 625 aa GQPAKNQAVT NVDRTVRSVK RHMGSDWSIE IDGKKYTAPE ISARILMKLK RDAEAYLGED ITDAVITTPA YFNDAQRQAT KDAGQIAGLN VLRIVNEPTA AALAYGLDKG EKEQRILVFD LGGGTFDVSL LEIGEGVVEV RATSGDNHLG GDDWDQRVVD WLVDKFKGTS GIDLTKOKMA MQRLREAAEK AKIELSSSQS TSINLPYITV DAOKNPLFLD EQLTRAEFQR ITQDLLDRTR KPFQSVIADT GISVSEIDHV VLVGGSTRMP AVTDLVKELT GGKEPNKGVN PDEVVAVGAA LQAGVLKGEV KDVLLLDVTP LSLGIETKGG VMTRLIERNT TIPTKRSETF TTADDNQPSV QIQVYQGERE IAAHNKLLGS FELTGIPPAP RGIPQIEVTF DIDANGIVHV TAKDKGTGKE NTIRIQEGSG LSKEDIDRMI KDAEAHAEED RKRREEADVR NQAETLVYQT EKFVKEQREA EGGSKVPEDT LNKVDAAVAE AKAALGGSDI SAIKSAMEKL GQESQALGQA IYEAAQAASQ ATGAAHPGGE PGGAHPGSAD DVVDAEVVDD GREAK Rv3044 FecB 16 MRSTVAVAVA AAVIAASSGC GSDQPAHKAS QSMITPTTQI AGAGVLGNDR 359 aa KPDESCARAA AAADPGPPTR PAHNAAGVSP EMVQVPAEAQ RIVVLSGDQL DALCALGLQS RIVAAALPNS SSSQPSYLGT TVHDLPGVGT RSAPDLRAIA AAHPDLILGS QGLTPQLYPQ LAAIAPTVFT AAPGADWENN LRGVGAATAR IAAVDALITG FAEHATQVGT KHDATHFQAS IVQLTANTMR VYGANNFPAS VLSAVGVDRP PSQRFTDKAY IEIGTTAADL AKSPDFSAAD ADIVYLSCAS EAAAERAAVI LDSDPWRKLS ANRDNRVFVV NDQVWQTGEG MVAARGIVDD LRWVDAPIN

TABLE 2 Immunodominant Cytosolic Mtb Proteins^(b) H37Rv Common SEQ Gene Names ID Product (length - aa) NO: Amino Acid Sequence^(c) Rv0577 None^(d) 6 See Table 1 Rv1827 CFP17 7 See Table 1 Rv1932 Tpx 9 See Table 1 Rv3418c GroES 11 See Table 1 Rv0054 Ssb 17 VAGDTTITIV GNLTADPELR FTPSGAAVAN FTVASTPRIY DRQTGEWKDG 164 aa EALFLRCNIW REAAENVAES LTRGARVIVS GRLKQRSFET REGEKRTVIE VEVDEIGPSL RYATAKVNKA SRSGGFGSGS RPAPAQTSSA SGDDPWGSAP ASGSFGGGDD EPPF Rv0652 RpIL 18 MAKLSTDELL DAFKEMTLLE LSDFVKKFEE TFEVTAAAPV AVAAAGAAPA 130 aa GAAVEAAEEQ SEFDVILEAA GDKKIGVIKV VREIVSGLGL KEAKDLVDGA PKPLLEKVAK EAADEAKAKL EAAGATVTVK Rv3029c FixA 19 MTNIVVLIKQ VPDTWSERKL TDGDFTLDRE AADAVLDEIN ERAVEEALQI 266 aa REKEAADGIE GSVTVLTAGP ERATEAIRKA LSMGADKAVH LKDDGMHGSD VIQTGWALAR ALGTIEGTEL VIAGNESTDG VGGAVPAIIA EYLGLPQLTH LRKVSIEGGK ITGERETDEG VFTLEATLPA VISVNEKINE PRFPSFKGIM AAKKKEVTVL TLAEIGVESD EVGLANAGST VLASTPKPAK TAGEKVTDEG EGGNQIVQYL VAQKII Rv3028c FixB 20 MAEVLVLVEH AEGALKKVSA ELITAARALG EPAAVVVGVP GTAAPLVDGL 318 aa KAAGAAKIYV AESOLVOKYL ITPAVDVLAG LAESSAPAGV LIAATADGKE IAGRLAARIG SGLLVDVVDV REGGVGVHSI FGGAFTVEAQ ANGDTPVITV RAGAVEAEPA AGAGEQVSVE VPAAAENAAR ITAREPAVAG DRPELTEATI VVAGGRGVGS AENFSVVEAL ADSLGAAVGA SRAAVDSGYY PGQFQVGQTG KTVSPQLYIA LGISGAIQHR AGMQTSKTIV AVNKDEEAPI FEIADYGVVG DLFKVAPQLT EAIKARKG Rv2428 AhpC2 21 MPLLTIGDQF PAYQLTALIG GDLSKVDAKQ PGDYFTTITS DEHPGKWRVV 195 aa FFWPKDFTFV CPTEIAAFSK LNDEFEDRDA QILGVSIDSE FAHFQWRAQH NDLKTLPFPM LSDIKRELSQ AAGVLNADGV ADRVTFIVDP NNEIQFVSAT AGSVGRNVDE VLRVLDALQS DELCACNWRK GDPTLDAGEL LKASA Rv0440 GroEL2 22 MAKTIAYDEE ARRGLERGLN ALADAVKVTL GPKGRNVVLE KKWGAPTITN 540 aa DGVSIAKEIE LEDPYEKIGA ELVKEVAKKT DDVAGDGTTT ATVLAQALVR EGLRNVAAGA NPLGLKRGIE KAVEKVTETL LKGAKEVETK EQIAATAAIS AGDQSIGDLI AEAMDKVGNE GVITVEESNT FGLQLELTEG MRFDKGYISG YFVTDPERQE AVLEDPYILL VSSKVSTVKD LLPLLEKVIG AGKPLLIIAE DVEGEALSTL VVNKIRGTFK SVAVKAPGFG DRRKAMLQDM AILTGGQVIS EEVGLTLENA DLSLLGKARK VVVTKDETTI VEGAGDTDAI AGRVAQIRQE IENSDSDYDR EKLQERLAKL AGGVAVIKAG AATEVELKER KHRIEDAVRN AKAAVEEGIV AGGGVTLLQA APTLDELKLE GDEATGANIV KVALEAPLKQ IAFNSGLEPG VVAEKVRNLP AGHGLNAQTG VYEDLLAAGV ADPVKVTRSA LQNAASIAGL FLTTEAVVAD KPEKEKASVP GGGDMGGMDF Rv2031c HspX 23 MATTLPVQRH PRSLFPEFSE LFAAFPSFAG LRPTFDTRLM RLEDEMKEGR Acr YEVRAELPGV DPDKDVDIMV RDGQLTIKAE RTEQKDFDGR SEFAYGSFVR 144 aa TVSLPVGADE DDIKATYDKG ILTVSVAVSE GKPTEKHIQI RSTN Rv2626c None^(d) 24 MTTARDIMNA GVTCVGEHET LTAAAQYMRE HDIGALPICG DDDRLHGMLT 143 aa DRDIVIKGLA AGLDPNTATA GELARDSIYY VDANASIQEM LNVMEEHQVR RVPVISEHRL VGIVTEADIA RHLPEHAIVQ FVKAICSPMA LAS Rv1211 None^(d) 25 MLGADQARAG GPARIWREHS MAAMKPRTGD GPLEATKEGR GIVMRVPLEG 75 aa GGRLVVELTP DEAAALGDEL KGVTS Rv1240 Mdh 26 VSASPLKVAV TGAAGQIGYS LLFRLASGSL LGPDRPIELR LLEIEPALQA 329 aa LEGV+VMELDD CAFPLLSGVE IGSDPQKIFD GVSLALLVGA RPRGAGMERS DLLEANGAIF TAQGKALNAV AADDVRVGVT GNPANTNALI AMTNAPDIPR ERFSALTRLD HNRAISQLAA KTGAAVTDIK KMTIWGNHSA TQYPDLFHAE VAGKNAAEVV NOQAWIEDEF IPTVAKRGAA ITDARGASSA ASAASATIDA ARDWLLGTPA DDWVSMAVVS DGSYGVPEGL ISSFPVTTKG GNWTIVSGLE IDEFSRGRID KSTAELADER SAVTELGLI Rv1626 None^(d) 27 MTGPTTDADA AVPRRVLIAE DEALIRMDLA EMLREEGYEI VGEAGDGQEA 205 aa VELAELHKPD LVIMDVKMPR RDGIDAASEI ASKRIAPIVV LTAFSQRDLV ERARDAGAMA YLVKPFSISD LIPAIELAVS RFREITALEG EVATLSERLE TRKLVERAKG LLQTKHGMTE PDAFKWIQRA AMDRRTTMKR VAEVVLETLG TPKDT Rv0733 Adk 28 VRVLLLGPPG AGKGTQAVKL AEKLGIPQIS TGELFRRNIE EGTKLGVEAK 181 aa RYLDAGDLVP SDLTNELVDD RLNNPDAANG FILDGYPRSV EQAKALHEML ERRGTDIDAV LEFRVSEEVL LERLKGRGRA DDTDDVILNR MKVYRDETAP LLEYYRDQLK TVDAVGTMDE VFARALRALG K Rv2461c ClpP 29 VSQVTDMRSN SQGLSLTDSV YERLLSERII FLGSEVNDEI ANRLCAQILL 200 aa LAAEDASKDI SLYINSPGGS ISAGMAIYDT MVLAPCDIAT YAMGMAASMG EFLLAAGTKG KRYALPHARI LMHQPLGGVT GSAADIAIQA EQFAVIKKEM FRLNAEFTGQ PIERIEADSD RDRWFTAAEA LEYGFVDHII TRAHVNGEAQ Rv0952 SucD 30 MTHMSIFLSR DNKVIVQGIT GSEATVHTAR MLRAGTQIVG GVNARKAGTT 303 aa VTHEDKGGRL IKLPVFGSVA EAMEKTGADV SIIFVPPTFA KDAIIEAIDA EIPLLVVITE GIPVQDTAYA WAYNLEAGHK TRIIGPNCPG IISPGQSLAG ITPANITGPG PIGLVSKSGT LTYQMMFELR DLGFSTAIGI GGDPVIGTTH IDAIEAFERD PDTKLIVMIG EIGGDAEERA ADFIKTNVSK PVVGYVAGFT APEGKTMGHA GAIVSGSSGT AAAKQEALEA AGVKVGKTPS ATAALAREIL LSL Footnotes to Tables 1 and 2: ^(a)identified by 2-D liquid phase electrophoresis the Mtb culture filtrate protein fractions ^(b)identified by 2-D liquid phase electrophoresis of cytosolic fractions. Some cytosolic proteins are also secreted, hence the presence of four proteins from Table 1 in Table 2. ^(c)These sequences, obtained from GenBank which includes the fully sequenced Mtb genome. The sequence shown in this table is the complete protein sequence encoded by the open reading frame. Secreted proteins are synthesized with an N terminal secreted signal sequence (“SEC-dependent signal secretion sequence”) which may include up to as many as 35 or 40 of the N-terminal residues. Signal sequences of several of the proteins are indicated in the table by underscore and italics. This sequenceis cleaved from the secreted protein. When used as immunogens, the secreted proteins lack this secreted signal sequence. Sequences were obtained using MS or MS/MS data of peptides generated by trypsin digestion and were identified using the MSFit (25) or Sequest (26) programs, respectively. ^(d)The present inventors and their colleagues were the first to identify a protein with a specific function or biological activity (stimulation of T cells in infected mice) for this previouslv recognized open reading frame of the Mtb genome.

A functional derivative thus includes a “homologue,” “fragment,” “variant,” “analogue,” or “chemical derivative” of the antigenic Mtb protein of this invention. “Functional derivatives” encompass “variants” and “fragments” regardless of whether the terms are used in the conjunctive or the alternative herein.

A functional derivative retains at least a portion of the function of the full length protein which permits its utility in accordance with the present invention, namely, the ability to induce heightened resistance to Mtb challenge when administered in mid-life to a BCG vaccinated subject

A “fragment” of the antigenic Mtb protein refers to any subset of the molecule, that is, a shorter peptide. An “analogue” of the antigenic Mtb protein refers to a non-natural molecule substantially similar to either the entire molecule or a fragment thereof.

Preferred fragments of the full length Mtb protein are booster vaccine epitopes which stimulate T_(H)1 cells from subjects primed by earlier BCG vaccination.

A “variant” refers to a polypeptide or peptide molecule substantially similar to either the entire protein or the fragment thereof. Variant peptides may be conveniently prepared by direct chemical synthesis using methods well-known in the art. A preferred group of variants are those in which at least one amino acid residue and preferably, only one, has been substituted by different residue. For a detailed description of protein chemistry and structure, see Schulz, G E et al., Principles of Protein Structure, Springer-Verlag, New York, 1978, and Creighton, T. E., Proteins: Structure and Molecular Properties, W.H. Freeman & Co., San Francisco, 1983, which are hereby incorporated by reference. The types of substitutions that may be made in the protein molecule may be based on analysis of the frequencies of amino acid changes between a homologous protein of different species, such as those presented in Table 1-2 of Schulz et al. (supra) and FIG. 3-9 of Creighton (supra). Based on such an analysis, conservative substitutions are defined herein as exchanges within one of the following five groups:

1 Small aliphatic, nonpolar or slightly polar Ala, Ser, Thr (Pro, Gly); residues 2 Polar, negatively charged residues and Asp, Asn, Glu, Gln; their amides 3 Polar, positively charged residues His, Arg, Lys; 4 Large aliphatic, nonpolar residues Met, Leu, Ile, Val (Cys) 5 Large aromatic residues Phe, Tyr, Trp.

The three amino acid residues in parentheses above have special roles in protein architecture. Gly is the only residue lacking a side chain and thus imparts flexibility to the chain. Pro, because of its unusual geometry, tightly constrains the chain. Cys can participate in disulfide bond formation, which is important in protein folding.

Another useful functional derivative is a fusion protein, a polypeptide that includes a functional fragment of the immunogenic Mtb protein. The presence of the fusion partner can alter the solubility, affinity and/or valency (defined here as the number of binding sites available per molecule) of the Mtb protein.

Homologues

A functional homologue must possess the above biological activity. In view of this functional characterization, use of homologous proteins from other mycobacterial species, including proteins not yet discovered, fall within the scope of the invention if these proteins have sequence similarity and the recited biochemical and biological activity.

To determine the percent identity of two amino acid sequences (or of two nucleic acid sequences), the sequences are aligned for optimal comparison purposes (e.g., gaps can be introduced in one or both of a first and a second amino acid or nucleic acid sequence for optimal alignment and non-homologous sequences can be disregarded for comparison purposes). In a preferred method of alignment, Cys residues are aligned.

In a preferred embodiment, the length of a sequence being compared is at least 30%, preferably at least 40%, more preferably at least 50%, even more preferably at least 60%, and even more preferably at least 70%, 80%, or 90% of the length of the reference sequence.

For example, when aligning a second sequence to a particular immunogenic Mtb protein, e.g., Ag85A (SEQ ID NO:1) having 295 amino acid residues, at least 90, preferably at least 118, more preferably at least 148, even more preferably at least 177, and even more preferably at least 207, 236 or 266 amino acid residues are aligned. The amino acid residues (or nucleotides) at corresponding amino acid positions (or nucleotide) positions are then compared. When a position in the first sequence is occupied by the same amino acid residue (or nucleotide) as the corresponding position in the second sequence, then the molecules are identical at that position (as used herein amino acid or nucleic acid “identity” is equivalent to amino acid or nucleic acid “homology”). The percent identity between the two sequences is a function of the number of identical positions shared by the sequences, taking into account the number of gaps, and the length of each gap, which need to be introduced for optimal alignment of the two sequences.

The comparison of sequences and determination of percent identity between two sequences can be accomplished using a mathematical algorithm. In a preferred embodiment, the percent identity between two amino acid sequences is determined using the Needleman and Wunsch (J. Mol. Biol. 48:444-453 (1970) algorithm which has been incorporated into the GAP program in the GCG software package (available at http://www.gcg.com), using either a Blossom 62 matrix or a PAM250 matrix, and a gap weight of 16, 14, 12, 10, 8, 6, or 4 and a length weight of 1, 2, 3, 4, 5, or 6. In yet another preferred embodiment, the percent identity between two nucleotide sequences is determined using the GAP program in the GCG software package (available at http://www.gcg.com), using a NWSgapdna.CMP matrix and a gap weight of 40, 50, 60, 70, or 80 and a length weight of 1, 2, 3, 4, 5, or 6. In another embodiment, the percent identity between two amino acid or nucleotide sequences is determined using the algorithm of E. Meyers and W. Miller (CABIOS, 4:11-17 (1989)) which has been incorporated into the ALIGN program (version 2.0), using a PAM120 weight residue table, a gap length penalty of 12 and a gap penalty of 4.

The protein sequences of the present invention can further be used as a “query sequence” to perform a search against public databases, for example, to identify other family members or related sequences. Such searches can be performed using the NBLAST and XBLAST programs (version 2.0) of Altschul et al. (1990) J. Mol. Biol. 215:403-10. BLAST nucleotide searches can be performed with the NBLAST program, score=100, wordlength=12 to obtain nucleotide sequences homologous to Mtb Ag85A-encoding nucleic acid molecules. BLAST protein searches can be performed with the XBLAST program, score=50, wordlength=3 to obtain amino acid sequences homologous to Mtb Ag85A protein molecules of the invention. To obtain gapped alignments for comparison purposes, Gapped BLAST can be utilized as described in Altschul et al. (1997) Nucleic Acids Res. 25:3389-3402. When utilizing BLAST and Gapped BLAST programs, the default parameters of the respective programs (e.g., XBLAST and NBLAST) can be used. See http://www.ncbi.nlm.nih.gov.

In another embodiment, a homologue is defined as having a sequence similarity the statistical significance of which results in a z value exceeding 10 when the sequence of the homologue is compared to the sequence of the native protein using a program such as BLAST (XBALST) above, or an earlier program such as FASTA or FASTP, coupled with a Monte Carlo analysis as described by W. R. Pearson and D. J. Lipman, Proc Natl Acad Sci USA., 85:2444-2448, 1988.

Thus, for example, a homologue of the Mtb Ag85A protein described above is characterized as having (a) functional activity of native Mtb Ag85A and (b) sequence similarity to a native Mtb Ag85A protein (SEQ ID NO:31) of at least about 30% (at the amino acid level), preferably at least about 50%, more preferably at least about 70%, even more preferably at least about 90%.

It is within the skill in the art to obtain and express such a protein using DNA probes based on the disclosed sequences of Mtb Ag85A. Then, the protein's biochemical and biological activity can be tested readily using art-recognized methods such as those described herein, for example, a standard T cell proliferation or IFNγ secretion assay. Preferred assays measure the functional characteristics of Mtb Ag85A such as stimulating T cells synthesis of cytokines, particularly IFNγ. The binding of Mtb Ag85A epitopes processed by antigen presenting cells to its cognate T cell receptor on, for example, T_(H)1 cells, transmits a signal that induces increased cytokine production; if the cytokine is a growth factor such as IL-2, it stimulates proliferation which can also be measured routinely.

All the native DNA sequences encoding the native proteins that are within the scope of this invention are publicly available on GenBank (or other public databases). A number of processes can be used to generate fragments, mutants and variants of the isolated DNA sequence. Small subregions or fragments of the nucleic acid encoding the immunogenic Mtb protein, for example 1-30 bases in length, can be prepared by standard, chemical synthesis.

Chemical Derivatives

A “chemical derivative” of the Mtb protein contains additional chemical moieties not normally a part of the peptide. Covalent modifications of the polypeptide or peptide are included within the scope of this invention. Such modifications may be introduced into the molecule by reacting targeted amino acid residues of the peptide with an organic derivatizing agent that is capable of reacting with selected side chains or terminal residues.

Covalent modifications of the polypeptide or peptide are included and may be introduced by reacting targeted amino acid residues of the peptide with an organic derivatizing agent that is capable of reacting with selected side chains or terminal residues.

Cysteinyl residues most commonly are reacted with α-haloacetates (and corresponding amines) to give carboxymethyl or carboxyamidomethyl derivatives. Cysteinyl residues also are derivatized by reaction with bromotrifluoroacetone, α-bromo-β-(5-imidozoyl)propionic acid, chloroacetyl phosphate, N- alkylmaleimides, 3-nitro-2-pyridyl disulfide, methyl 2-pyridyl disulfide, p-chloromercuribenzoate, 2-chloromercuri-4-nitrophenol, or chloro-7-nitrobenzo-2-oxa-1,3-diazole.

Histidyl residues are derivatized by reaction with diethylprocarbonate (pH 5.5-7.0) which agent is relatively specific for the histidyl side chain. p-bromophenacyl bromide also is useful; the reaction is preferably performed in 0.1 M sodium cacodylate at pH 6.0.

Lysinyl and amino terminal residues are reacted with succinic or other carboxylic acid anhydrides. Derivatization with these agents reverses the charge of the lysinyl residues. Other suitable reagents for derivatizing α-amino-containing residues include imidoesters such as methylpicolinimidate; pyridoxal phosphate; pyridoxal; chloroborohydride; trinitrobenzenesulfonic acid; O-methylisourea; 2,4 pentanedione; and transaminase-catalyzed reaction with glyoxylate.

Arginyl residues are modified by reaction with one or several conventional reagents, including phenylglyoxal, 2,3-butanedione, 1,2-cyclohexanedione, and ninhydrin. Such derivatization requires that the reaction be performed in alkaline conditions because of the high pK_(a) of the guanidine functional group. Furthermore, these reagents may react with the groups of lysine as well as the arginine ε-amino group.

Modification of tyrosyl residues has permits introduction of spectral labels into a peptide. This is accomplished by reaction with aromatic diazonium compounds or tetranitromethane. Most commonly, N-acetylimidizol and tetranitromethane are used to create O-acetyl tyrosyl species and 3-nitro derivatives, respectively.

Carboxyl side groups (aspartyl or glutamyl) are selectively modified by reaction with carbodiimides (R′—N—C—N—R′) such as 1-cyclohexyl-3-(2-morpholinyl-(4-ethyl) carbodiimide or 1-ethyl-3-(4-azonia-4,4-dimethylpentyl) carbodiimide.

Aspartyl and glutamyl residues are converted to asparaginyl and glutaminyl residues by reaction with ammonium ions. Conversely, glutaminyl and asparaginyl residues may be deamidated to the corresponding glutamyl and aspartyl residues. Deamidation can be performed under mildly acidic conditions. Either form of these residues falls within the scope of this invention.

Derivatization with bifunctional agents is useful for cross-linking the peptide to a water-insoluble support matrix or other macromolecular carrier. Commonly used cross-linking agents include 1,1-bis(diazoacetyl)-2-phenylethane, glutaraldehyde, N-hydroxysuccinimide esters, esters with 4-azidosalicylic acid, homobifunctional imidoesters, including disuccinimidyl esters such as 3,3′-dithiobis(succinimidylpropionate), and bifunctional maleimides such as bis-N-maleimido-1,8-octane.

Derivatizing agents such as methyl-3-[(p-azidophenyl)dithio]propioimidate yield photoactivatable intermediates that are capable of forming crosslinks in the presence of light. Alternatively, reactive water-insoluble matrices such as cyanogen bromide-activated carbohydrates and the reactive substrates described in U.S. Pat. Nos. 3,969,287; 3,691,016; 4,195,128; 4,247,642; 4,229,537; and 4,330,440 are employed for protein immobilization.

Other chemical modifications include hydroxylation of proline and lysine, phosphorylation of the hydroxyl groups of seryl or threonyl residues, methylation of the α-amino groups of lysine, arginine, and histidine side chains (T. E. Creighton, supra), acetylation of the N-terminal amine, and, in some instances, amidation of the C-terminal carboxyl.

Such chemically modified and derivatized moieties may improve the protein's or peptide's solubility, absorption, biological half life, and the like. These changes may eliminate or attenuate undesirable side effects of the proteins in vivo. Moieties capable of mediating such effects are disclosed, for example, in Remington's Pharmaceutical Sciences, Mack Publishing Company, Easton Pa. (Gennaro 18th ed. 1990).

Vaccine Compositions and their Formulation

This invention includes a vaccine composition for boosting anti-Mtb protective immunity during midlife in a BCG-vaccinated subject. An Mtb immunogenic protein preferably one of the proteins described herein in more detail, is formulated as the active ingredient in a vaccine composition.

The vaccine compositions preferably comprises any of the following proteins (in their secreted form if they are secreted proteins), or preferably, a mixture of two or more of: Rv3804c, Rv1886c, Rv0129c, Rv1860, Rv0934, Rv0577, Rv1827, Rv3841, Rv1932, Rv1352, Rv3418c, Rv3875, Rv1810, Rv1980c, Rv0350, Rv3044, Rv0054, Rv0652, Rv3029c, Rv3028c, Rv2428, Rv0440, Rv2031c, Rv2626c, Rv1211, Rv1240, Rv1626, Rv0733, Rv2461c, and Rv0952. A most preferred vaccine composition includes Rv3804c or one or more epitopes thereof as a single or one of a mixture of immunogenic molecules.

The vaccine may also comprises one or more peptides or other functional derivatives of these proteins as described, or DNA encoding the protein (in the form of a DNA vaccine), and a pharmaceutically and immunologically acceptable vehicle or carrier. In one embodiment, the vaccine comprises a fusion protein which includes at least one immunogenic epitope of the Mtb protein.

As described in more detail, the vaccine composition preferably also comprises an adjuvant or other immune stimulating agent. For use in vaccines, the Mtb antigenic protein or epitope-bearing peptide thereof is preferably produced recombinantly, preferably in prokaryotic cells as noted above.

Full length proteins or longer multiple epitope-bearing fragments are preferred immunogens, in particular, those reactive with T cells, particularly those that stimulate IFNγ production by T cells. If a shorter epitope-bearing fragment, for example containing 20 amino acids or less, is the active ingredient of the vaccine, it is advantageous to couple the peptide to an immunogenic carrier to enhance its immunogenicity or to fuse a number of repeating units of the epitope in a single polypeptide chain. Such coupling techniques are well known in the art, and include standard chemical coupling techniques using linker moieties such as those available from Pierce Chemical Company, Rockford, Ill. Suitable carriers are described below.

Another embodiment is a fusion protein which comprise the Mtb protein or epitope-bearing peptide region fused linearly to an additional amino acid sequence. Because of the ease with which recombinant materials can be manipulated, multiple copies a selected epitope-bearing region may be included in a single fusion protein molecule. Alternatively, several different epitope-bearing regions that are not part of the same protein in its native form can be “mixed and matched” in a single fusion polypeptide.

The active ingredient, preferably a recombinant product, is preferably administered as a protein or peptide vaccine. However, as noted, the vaccine composition may also comprise a DNA vaccine (e.g., Hoffman, S L et al., 1995, Ann N Y Acad Sci 772:88-94; Donnelly, J J et al., 1997, Annu Rev Immunol 15:617-48; Robinson, H L, 1997, Vaccine. 15: 785-787, 1997; Wang, R et al., 1998, Science. 282: 476-480, 1998; Gurunathan, S et al., 2000, Annu Rev Immunol 18:927-74; Restifo, N P et al., 2000, Gene Ther. 7:89-92). The DNA encodes the Mtb protein or one or more epitope(s) thereof, and may be optionally linked to DNA encoding a protein that promotes expression of the Mtb protein in the host after immunization. Known examples of such proteins include heat shock protein 70 (HSP70) (Srivastava, P K et al., 1994. Immunogenetics 39:93-8; Suto, R et al., 1995, Science 269:1585-8; Arnold-Schild, D et al., 1999, J Immunol 162:3757-60; Binder, R J et al., 2000, Nature Immunology 2:151-155; Chen, C H et al., 2000, Cancer Res 60:1035-42) or translocation proteins such herpesvirus protein VP22 (Elliott, G, and O'Hare, P., 1997. Cell 88:223-33; Phelan, A et al., 1998, Nat Biotechnol 16:440-3; Dilber, M S et al., 1999. Gene Ther 6:12-21) or domain 11 of Pseudomonas aeruginosa exotoxin A (ETA) (Jinno, Y et al., J Biol. Chem. 264: 15953-15959, 1989; Siegall, C B et al., Biochemistry. 30: 7154-7159, 1991; Prior, T I et al., Biochemistry. 31: 3555-3559, 1992; Fominaya, J et al., J. Biol. Chem. 271: 10560-10568, 1996; Fominaya, J et al., Gene Ther. 5: 521-530, 1998; Goletz, T J et al., Hum Immunol. 54: 129-136, 1997).

In another embodiment, the vaccine is in the form of a strain of bacteria (preferably a known “vaccine strain”) which has been genetically transformed to express the Mtb protein or epitope-bearing peptide. Some known vaccine strains of Samonella are a live vaccine strain of Salmonella dublin, termed SL5928 aroA148fliC(i)::Tn10 and S. typhimurium LB5000 hsdSB121 leu-3121 (Newton S. M. et al., Science 1989, 244: 70

A Samonella strain expressing the Mtb protein or fragment of this invention may be constructed using known methods. Thus, a plasmid encoding the protein or peptide. The plasmid may first be selected in an appropriate host, e.g., E. coli strain MC1061. The purified plasmid is then introduced into S. typhimurium strain LB5000 so that the plasmid DNA is be properly modified for introduction into Samonella vaccine strains. Plasmid DNA isolated from LB5000 is introduced into, e.g., S. dublin strain SL5928 by electroporation. Expression of the Mtb protein or fragment encoded by the plasmid in SL5928 can be verified by Western blots of bacterial lysates and antibodies specific for the relevant antigen or epitope.

Formulation of the Polypeptide Vaccine

The protein/peptide composition that is formulated as a vaccine can be the whole target protein or fragments thereof. The immunogenicity of the present Mtb protein/peptide immunogen a is enhanced in the presence of exogenous adjuvants, immune stimulants, depot materials, etc.

In some cases, the immunogenicity or effectiveness of the Mtb protein/peptide may benefit from its being conjugated to a suitable carrier, usually another larger protein molecule that is foreign to the host being immunized. In such a construct, multiple copies of the polypeptide may be conjugated to a single larger carrier molecule. The carrier may have properties which facilitate transport, binding, absorption or transfer of the polypeptide immunogen. Conjugation between proteinaceous materials is readily accomplished using conventional methods, e.g., bifunctional cross-linkers as binding agents (Means et al., Bioconjugate Chem. 1:2-12 (1990)). Examples of suitable carriers are the tetanus toxoid, the diphtheria toxoid, serum albumin, keyhole limpet hemocyanin proteins E. coli pilin protein 99, BSA, rotavirus VP6 protein, and the like. Conjugates including these “universal” carriers can stimulate T cell responses (preferably T helper cells) in a less MHC-restricted manner than would occur without them.

The immunogenic Mtb protein/peptide may be combined or mixed with various fluids and with other substances known in the art. The polypeptide is formulated conventionally using methods well-known for formulation of such vaccines. The active ingredient is generally dissolved or suspended in an acceptable carrier such as water, saline or buffered saline.

The vaccine composition may further comprise one or more adjuvants or immunostimulating agents. Examples of adjuvants or agents that may add to the effectiveness of the protein as an immunogen include aluminum hydroxide, aluminum phosphate, aluminum potassium sulfate (alum) beryllium sulfate, silica, kaolin, carbon, water-in-oil emulsions, oil-in-water emulsions, muramyl dipeptide, bacterial endotoxin, lipid X, whole organisms or subcellular fractions of the bacteria Propionobacterium acnes or Bordetella pertussis, polyribonucleotides, sodium alginate, lanolin, lysolecithin, vitamin A, saponin and saponin derivatives (such as QS-21 a purified triterpene glycoside from the South American tree Quillaja saponarial(Soltysik, S et al., Ann N Y Acad Sci. (1993) 690:392-395, liposomes, levamisole, DEAE-dextran, blocked copolymers or other synthetic adjuvants. Another adjuvant is ISAF-1 (5% squalene, 2.5% pluronic L121, 0.2% Tween 80 in phosphate-buffered solution with 0.4 mg of threonyl-muramyl dipeptide (Kwak, L W et al., (1992) N. Engl. J. Med., 327: 1209-1238). Such adjuvants are available commercially from various sources, for example, Merck Adjuvant 65 (Merck and Company, Inc., Rahway, N.J.) or Freund's Incomplete Adjuvant and Complete Adjuvant (Difco Laboratories, Detroit, Mich.). Aluminum is approved for human use. The vaccine material may be adsorbed to or conjugated to beads such as latex or gold beads, ISCOMs, and the like. General methods to prepare vaccines are described in Remington's Pharmaceutical Science; Mack Publishing Company Easton, Pa. (latest edition).

A most preferred adjuvant for the Mtb proteins, such as exemplified for Antigen 85A, is monophosphoryl lipid A adjuvant solubilized in 0.02% triethanolamine plus an effective amount of recombinant IL-2 cytokine.

Liposomes are pharmaceutical compositions in which the active protein is contained either dispersed or variously present in corpuscles consisting of aqueous concentric layers adherent to lipidic layers. The active protein is preferably present in the aqueous layer and in the lipidic layer, inside or outside, or, in any event, in the non-homogeneous system generally known as a liposomic suspension. The hydrophobic layer, or lipidic layer, generally, but not exclusively, comprises phospholipids such as lecithin and sphingomyelin, steroids such as cholesterol, more or less ionic surface active substances such as dicetylphosphate, stearylamine or phosphatidic acid, and/or other materials of a hydrophobic nature. Adjuvants, including liposomes, are discussed in the following references, incorporated herein by reference: Gregoriades, G. et al., Immunological Adjuvants and Vaccines, Plenum Press, New York, 1989 Michalek, S. M. et al., Curr. Top. Microbiol. Immunol. 146:51-58 (1989).

Additional discussion of vaccine design, particularly controlled release systems, can be found in Powell, M. F. et al. (eds), Vaccine Design: The Subunit and Adjuvant Approach, Powell, M. F. et al. (eds), Plenum Press, New York 1995, p 389-412. Controlled release systems are already used in humans as “depots” to deliver drugs and hormones (Langer, R. 1990, Science 249: 1527-1533). Such systems may have a significant impact on immunization as they can be designed to deliver controlled amounts of antigen continuously or in spaced pulses at predetermined rates (Cohen et al., 1991, Pharm. Res. 8:713-720; Eldridge et al., 1991a, Mol. Immunol. 28:287-294; Gander et al. 1993, in: Proc. Int. Syn. Control. Rel. Bioact. Mater., Controlled Release Society, Washington, D.C., pp. 65-66), while simultaneously protecting undelivered antigen from rapid degradation in vivo. Controlled release microspheres have considerable potential for oral immunization (Edelman et al., 1993, Vaccine 11:155-158; Eldridge et al., 1990, J. Control. Rel. 11:205-214; McQueen et al., 1993, Vaccine 11:201-206; Moldoveanu et al., 1989, Curr Top. Microbiol. Immunol. 146:91-99; O'Hagan et al., 1993b, Vaccine 11: 149-154; Reid et al. 1993, Vaccine 11:159-167). Other potential advantages of polymeric controlled release systems include: lower dosage requirements leading to decreased cost; localized or targeted delivery of antigen to antigen-presenting cells or the lymphatic system; more than one antigen may be encapsulated, facilitating the design of a formulation that can immunize an individual against more than one protein or against several epitopes of an Mtb protein in a single injection; and improved patient compliance. In addition, controlled release systems may reduce the number of vaccine doses required for optimal vaccination to a single injection.

Microspheres are particularly suited as controlled release vaccine carriers for two reason: (1) particles greater than 10 μm in diameter are capable of providing a long-term persistence of antigen at the site of injection which may be necessary for a sustained high-level antibody immune response and (2) microparticles in the size range of 1-10 μm are readily phagocytosed by macrophages (Eldridge et al., 1989, Adv. Exp. Med. Biol. 251:192202; Tabata et al., 1988, Biomaterials 9:356-362; J. Biomed Mater Res. 22:837-858) leading to direct intracellular delivery of antigen to antigen-presenting cells.

Microsphere phagocytosis by macrophages may be increased by altering the surface characteristics, as microspheres with hydrophobic surfaces are generally more readily phagocytosed than those with hydrophilic surfaces (Tabata et al., 1988, Biomaterials 9:356-362; Tabata et al., 1990, Crit. Rev. Ther Drug Carrier Syst. 7:121-148).

Among the advantages of using polymer microspheres for vaccine delivery is the ability to control the time following administration at which the antigen is released. This capability allows the fabrication of a single-injection formulation that releases multiple “pulses” of vaccine at predetermined times following administration (Gilley et al., 1992, In: Proc. Int. Symp. Control. Rel. Bioact. Mater, Controlled Release Society, Orlando, pp. 110-111). Antigen release kinetics from polymer microspheres can be controlled to a great extent by the simple manipulation of such variable as polymer composition and molecular weight, the weight ratio of vaccine to polymer (i.e., the vaccine loading), and microsphere size (Hanes et al., In: Reproductive Immunology, 1995, R. Bronson et al., eds, Blackwell. Oxford).

Vaccine formulations that contain a combination of both small (1-10 μm) and larger (20-50 μm) microspheres may produce higher and longer-lasting responses compared to the administration of vaccine encapsulated in microspheres with diameters of exclusively 1-10 or 20-50 μm (Eldridge et al., 1991a, Mol. Immunol. 28287-294). In one study, tetanus toxoid (TT)-containing microspheres were tailored to produce a strong priming antigen dose released over the first few days after injection followed by two “boosting” doses released after 1 and 3 months, respectively, in order to mimic conventional vaccination schedules (Gander et al., supra).

The most widely used polymers for vaccine microencapsulation have been the polyesters based on lactic and glycolic acid. These polymers have several advantages, including extensive data on their in vitro and in vivo degradation rates (Lewis, 1990, In: Biodegradable Polymers as Drug Delivery Systems (Chasin and Langer, eds.), Dekker, New York, pp. 1-41; Tice and Tabibi, 1992, In: Treatise on Controlled Drug Delivery (A. Kydonieus, ed.), Dekker, New York, pp. 315-339, and FDA approval for a number of clinical applications in humans such as surgical sutures (Gilding et al., 1979, Polymer 20:1459-1464; Schneider, 1972, U.S. Pat. No. 3,636,956) and a 30-day microsphere-based controlled delivery system for leuprolide acetate (Lupron Depot) (Okada et al., 1991, Pharm. Res. 8:787-791).

There are several interesting alternatives to the lactide/glycolide polyesters. For example, some biodegradable polymers degrade to give molecules with adjuvant properties, and may prove particularly useful as carriers of more weakly immunogenic antigens. Because of the know adjuvanticity of L-tyrosine derivatives (Wheeler et al, 1982, Int. Arch. Allergy Appl. Immunol. 69:113-119; Wheeler et al., 1984, Int. Arch. Allergy Appl. Immunol. 75:294-299), a polymer based on a dityrosine derivative was synthesized by Langer and colleagues (Kohn et al., 1987, Biomaterials 7:176-182) and was studied using the model antigen bovine serum albumin, BSA (Kohn et al., 1986, J. Immunol. Methods 95:31-38). Biodegradable poly (CTTH iminocarbonate) was selected since its primary degradation product N-benzyloxycarbonyl-L-tyrosyl-L-tyrosine hexyl ester (CTTH), was found to be as potent an adjuvant as complete Freund's (CFA) and muramyl dipeptide (MDP).

Because of its inherent propensity to be phagocytosed by macrophages (Tabata et al., 1986, J. Bioact. Compat. Polym. 1:32-46) and its extensive use in pharmaceutical and medical applications, gelatin is a useful polymer for vaccine microencapsulation (Tabata et al., 1993, in: Proc. Int. Symp. Control. Rel. Bioact. Mater, Controlled Release Society, Washington, D.C., pp. 392-393). Gelatin microspheres have also been used to encapsulate immunostimulators, such as MDP and interferon-α (Tabata et al., 1987, J. Pharm. Pharmacol. 39:698-704; 1989b, Pharm. Res. 6:422-427). Microsphere-encapsulated MDP activated macrophages in much shorter periods than did free MDP at concentrations approximately 2000 times lower. A combination of MDP and vaccine-containing gelatin microspheres may yield a very potent vaccine formulation.

Liposomes are often unstable in vivo, most likely because of their rapid destruction by macrophages and high-density lipoproteins (Schreier et al., 1987, J. Control. Rel. 5: 187-192), and therefore provide only a brief antigen depot effect when injected subcutaneously or intramuscularly (Eppstein et al., 1985, Proc. Natl. Acad. Sci. USA 82:3688-3692; Weiner et al., 1985, J. Pharm. Sci. 74:922-925). One approach to extending the in vivo lifetime of liposomes (Cohen et al., 1991, Proc. Natl. Acad. Sci. USA 88:10440-10444) was use of alginate polymers to encapsulate vaccine-containing liposomes into microspheres, thereby protecting them from rapid destruction in vivo. Enzymatically activated microencapsulated liposomes (MELs) that are capable of providing pulsatile vaccine release kinetics have also been prepared (Kibat et al., 1990, FASEB J. 4:2533-2539). MELs are also expected to show increased stability as a carrier for oral administration.

Microsphere Production

A variety of methods may be used to prepare vaccine-loaded polymer microspheres that are capable of a wide range of release patterns and durations. The method of choice usually is determined by the relative compatibility of the process conditions with the antigen (e.g., the method that results in the least loss of vaccine immunogenicity) and the polymer excipient used, combined with the ability of the method to produce appropriately sized microspheres.

Solvent evaporation techniques are popular because of their relative ease of preparation, amenability to scaleup, and because high encapsulation efficiencies can be attained. Of particular importance for vaccines that are sensitive to organic solvents may be the multiple emulsion technique (Cohen et al., 1991, Pharm. Res., supra). Spray drying and film casing techniques have also been used to prepare monolithic polymer microspheres.

Microcapsules consist of a vaccine-loaded core surrounded by a thin polymer membrane and, as a result, are often referred to as “reservoir” systems.

Carrier and vaccine stability during device development, storage, and in vivo depoting are a matte for concern. Polypeptide antigens may have with fragile three-dimensional structures that are vital to the immunogenicity of the vaccine. This three-dimensional structure may be compromised or lost as the antigen denatures or aggregates. Exposure to organic solvents, rehydration after lyophilization on exposure to moisture, or complex chemical interactions with the polymer excipient or other chemicals in the preparation of a controlled release device may result in loss or reduction of immunogenicity of protein-based vaccines. The following documents describe stabilization of complex antigens (Arakawa et al., 1993, Adv. Drug Deliv. Rev. 10:1-28; Liu et al., 1991, Biotechnol. Bioeng. 37:177-184; Volin and Klibanov, 1989, In: Protein Function: A Practical Approach (T. E. Creighton, ed.). IRL Press, Oxford, pp. 1-24).

An advantage of polymer microsphere formulations is that many polymers are stable at room temperature for extended periods of time if kept dry. For example, lactide/glycolide polyesters have been reported to be stable if kept dry and below about 40° C. (Aguado et al., 1992, Immunobiology 184:113-125). In addition, vaccine can be stored in the dry state within microsphere formulations, an important advantage considering susceptibility of some proteins to moisture-induced aggregation (Liu et al., supra).

The vaccine compositions preferably contain (1) an effective amount of the immunogenic Mtb polypeptide together with (2) a suitable amount of a carrier molecule or, optionally a carrier vehicle, and, if desired, (3) preservatives, buffers, and the like. Descriptions of vaccine formulations are found in Voller, A. et al., New Trends and Developments in Vaccines, University Park Press, Baltimore, Md. (1978).

In one embodiment, the vaccine composition includes one or more cytokines such as IL-2, GM-CSF, IL-4 and the like. Proinflammatory chemokines may be added, e.g., interferon inducible protein 10 and MCP-3 (Biragyn A et al., Nature Biotechnol. (1999) 17:253-258). In general, it appears that any cytokine or chemokine that induces inflammatory responses, recruits antigen presenting cells (APC) and promotes targeting of APC for chemokine receptor-mediated uptake of the polypeptide antigen leading to the generation of critical T cells, is useful in the present vaccine formulation.

As with all immunogenic compositions for eliciting cell-mediated immunity, the immunogenically effective amounts of the polypeptides of the invention must be determined empirically. Factors to be considered include the immunogenicity of the native polypeptide, whether or not the polypeptide will be complexed with or covalently attached to an adjuvant or carrier protein or other carrier and the route of administration and the number of immunizing doses to be administered. Such factors are known in the vaccine art, and it is well within the skill of immunologists to make such determinations without undue experimentation.

The proportion of the protein immunogen and the adjuvant can be varied over a broad range so long as both are present in effective amounts. For example, aluminum hydroxide can be present in an amount of about 0.5% of the vaccine mixture (Al₂O₃ basis).

After formulation, the vaccine composition may be incorporated into a sterile container which is sealed and stored at a low temperatures, for example 4° C. or −20° C. or −80° C. Alternatively, the material may be lyophilized which permits longer-term storage in a stabilized form.

Administration and Dosage

The vaccines are administered as is generally understood in the art. Ordinarily, systemic administration is by injection; however, other effective means of administration are known. With suitable formulation, polypeptide vaccines may be administered across the mucus membrane using penetrants such as bile salts or fusidic acids in combination, usually, with a surfactant. Transcutaneous administration of polypeptides is also known. Oral formulations can also be used.

Dosage levels depend on the mode of administration, the nature of the subject, and the nature of carrier/adjuvant formulation. Preferably, an effective amount of the protein or polypeptide is between about 0.01 μg/kg and about 1 mg/kg body weight. The amount of the immunogen per dose can range from about 0.01 mg to 100 mg of protein per subject per injection. A preferably range is from about 0.2 to 2 mg per dose. A suitable unit dose size is about 0.5 ml. Accordingly, a unit dosage form for subcutaneous injection could comprise 0.5 mg of immunogen admixed with 0.5% aluminum hydroxide in 0.5 ml.

Administration is preferably by injection on one or multiple occasions to boost the immune system to a state of systemic immunity. In general, multiple administrations of the vaccine in a standard immunization protocol are used, as is standard in the art. For example, the vaccines can be administered at approximately two to six week intervals, preferably monthly, for a period of from one to six inoculations in order to provide protection.

In a preferred embodiment, a BCG-vaccinated human subject receives a single booster injection of the Mtb protein at the age of about 10 years. After this first booster dose of the vaccine, the subject may optionally receive additional injections if this is determined to be efficacious, e.g., once a month for 6 months, but preferably no more than annually. It is within the skill of the art to determine empirically how many doses and what magnitude of dose are deemed optimal.

The vaccine may be administered by any conventional route including oral and parenteral. Examples of parenteral routes are subcutaneous, intradermal, transcutaneous, intravenous, intramuscular, etc.

Vaccination with the vaccine composition will result in a systemic immune response, which includes preferably a cell-mediated immune response and may also include an antibody response. This should provide an antimicrobial therapeutic effect and/or result in a activated T lymphocytes of various classes. In addition such T cells have a number of research uses that are evident to those skilled in the art.

Having now generally described the invention, the same will be more readily understood through reference to the following examples which are provided by way of illustration, and are not intended to be limiting of the present invention, unless specified.

EXAMPLE I Materials and Methods

Growth of M. tuberculosis, and Preparation of Culture Filtrate and Cytosolic Proteins

M. tuberculosis H₃₇Rv (ATCC 27294) was obtained from the American Type Culture Collection (Rockville, Md.). Initially, this strain was inoculated from a 1-mL frozen stock of approximately 10⁸ CFU/mL into 10 mL of glycerol-alanine-salts medium (Takayama, K et al., J. Lipid Res. 1975, 16:308-317). This initial culture was expanded to a total of 30 liters as described by Sonnenberg et al., supra. After incubation at 37° C. for 14 days with gentle agitation the culture supernatant was separated from the cells by filtration through a 0.2 μm membrane. The cells were collected, washed three times with PBS pH 7.4 and frozen at −70° C. until needed. The culture filtrate was concentrated by ultrafiltration with a 10 kDa molecular cut off membrane, dialyzed against 10 mM ammonium bicarbonate (Dobos, K M et al., Infect. Immun. 1996, 63:2846-285319), and the protein concentration determined by the bicinchoninic acid (BCA) protein assay (Smith, P K et al., Anal. Biochem. 1985, 150:76-85). Three lots of cells and CFPs were prepared in this fashion and pooled.

The M. tuberculosis H37Rv cells (103.2 g) were inactivated with 2.4 megarads of γ-irradiation. These cells were suspended in 50 mL of PBS pH 7.4 containing 0.06% DNase, 0.06% RNase, 0.07% pepstatin, 0.05% leupeptin, and 20 mM PMSF. The cell suspension was and passed through a French Press (American Instrument Co., Silver Spring, Md.) six times at 1,500 psi. The resulting lysate was diluted with 2 vol of the cell suspension buffer and centrifuged at 3,000×g for 5 minutes to remove unbroken cells. The supernatant was collected and subjected to centrifugation at 27,000×g, 4° C. for 1 h to remove cell wall material followed by centrifugation at 100,000×g, 4° C. for 4 h to remove cell membranes. The final supernatant (cytosol fraction) was collected and exhaustively dialyzed against 10 mM ammonium bicarbonate using a 3,500 Da molecular weight cutoff membrane. The final protein concentration of the cytosol was determined with BCA protein assay.

Preparative Liquid-Phase Isoelectric Focusing

CFPs (500 mg) and cytosol proteins (one lot of 100 mg and another of 150 mg) were each solubilized in 60 mL of a buffer containing 8M urea, 1 mM DTT, 5% glycerol, 2% NP-40, and 2% ampholytes (pH 3.0 to 10.0 and pH 4.0 to 6.5 in a ratio of 1:4) (“Pharmalytes,” Pharmacia Biotech AB, Uppsala, Sweden) and loaded on a Bio-Rad Rotofor System (Hercules, Calif.). The Rotofor apparatus was cooled to 4° C. Constant power (12 W) was applied until the voltage stabilized at approximately 1400 V. Focusing was continued for an additional 30 minutes and then terminated. The individual IEF fractions were harvested and their pH value determined. Finally, each IEF fraction was dialyzed against 10 mM ammonium bicarbonate using a 3,500 Da molecular cutoff membrane, the protein concentrations were determined using the BCA assay, and an aliquot (10 μg) was subjected to SDS-PAGE (Laemmli, U. K., Nature 1970, 227, 680-685) and the proteins visualized by staining with silver-nitrate (Morrissey, J. H., Anal. Biochem. 1981, 117, 307-310).

Preparative SDS PAGE and Electroelution

Preparative SDS-PAGE was performed on 0.2 to 10 mg aliquots of individual preparative IEF fractions. Briefly, each preparative IEF fraction was prepared for SDS-PAGE by the addition of 0.2 vol of 5× SDS-PAGE sample buffer (Laemmli, supra) and heating at 100° C. for 10 min. The reduced samples were loaded on 16×20 cm polyacrylamide gels that were comprised of a 6% stack over a 15% resolving gel. The stacking gel contained a single 13 cm sample well. Electrophoresis was performed at 35 mA per gel until the dye front was approximately 2 cm from the bottom of the gel. The gels were subsequently soaked for 15 to 20 min in 10 mM ammonium bicarbonate, cut to the appropriate size (14×16 cm), and transferred to a Bio-Rad Whole Gel Eluter according to manufacturer's instructions. The proteins were eluted from the gel using 250 mA constant current for 1 hour (Andersen et al., 1993, supra). Thirty protein fractions (approximately 2.5 mL each) were harvested, dialyzed against 10 mM ammonium bicarbonate using a 3,500 Da molecular cutoff membrane, and the protein concentration of each fraction was determined using the BCA protein assay. An aliquot (˜2 μg) of each preparative SDS-PAGE fraction was run on a 10×7.5 cm SDS-polyacrylamide gel and proteins visualized by staining with silver nitrate. The remaining quantity of each fraction was filter sterilized with a 0.2 um filter (Gelman, Ann Arbor, Mich.), and lyophilized.

In-Gel Digestions and Mass Spectrometry

An aliquot of protein (5-10 μg) was suspended in IEF sample buffer (Sonnenberg et al., supra) and applied to a 6% polyacrylamide IEF tube gel (1.5 mm by 6.5 cm) containing 5% ampholytes (pH 3 to 10 and 4 to 6.5 in a ratio of 4:1). The proteins were focused for 3 h at 1 kV. The tube gels were subsequently soaked in sample transfer buffer (Dunbar, B S et al., Methods Enzymol. 1990, 182:441-459) for 20 min and placed on a 15% preparative SDS-polyacrylamide gel (7.5 cm by 10 cm by 1.5 mm). Electrophoresis in the second dimension was carried out at 15 mA per gel for approximately 1.5 h. The gels were stained with Coomassie brilliant blue R-250 in 10% acetic acid and 50% methanol, and destained with 5% methanol 7% acetic acid. The gels were completely rehydrated in water, and the protein spots of interest were excised from the gel, and cut into small pieces. The proteins were destained, digested with modified trypsin (Boehringer Mannheim, Mannheim, Germany) and the peptides extracted with 60% acetonitrile, 0.1% TFA (Hellman, U et al., Anal. Biochem. 1995, 224:451-45524). The peptides were dried and suspended in 15 μl of 5% acetonitrile, 0.1% TFA and separated on a 15×0.1 cm C18 microbore reversed-phase column (Vydac, Hesperia, Calif.) connected to a Waters 2690 Separation Module (Milford, Mass.). The peptides were eluted with an increasing acetonitrile gradient at a flow rate of 20 μl per min. The reversed-phase effluent was introduced directly into a Finnigan LCQ (Thermoquest, San Jose, Calif.) electrospray mass spectrometer, and the peptides were analyzed by MS or MS-MS. The ES needle was operated at 6 kV with a sheath gas flow of N₂ at 40 and a capillary temperature of 100° C. MS-MS was performed on the fly of the most dominant ion of the previous MS scan and the collision energy was set at 40%. MS and MS-MS data of the peptides was matched to M. tuberculosis proteins using MS Fit (Baker, P. R. and Clauser, K. R., http://prospector.ucsf.edu) and the SEQUEST software (Eng, J K et al., J. Am. Soc. Mass Spectrom. 1994, 5:976-989; Yates, J R III, et al., Anal. Chem. 1995, 67:1426-1436), respectively. Both programs were set to consider oxidation of methionine (+16.0) and polyacrylamide modification of cysteine (+71.0). Mass tolerances of 1.0 Da for intact peptide ions and 0.5 Da for fragment ions were employed.

Infection of Mice with M. tuberculosis H37Rv and Harvesting of Splenocytes.

Fourteen C57B1/6 mice were infected by intravenous (iv) challenge with 1×10⁵ cfu of M. tuberculosis H₃₇Rv per animal (Orme, I. M., J. Immunol. 1987:138, 293-298). Seven infected mice and seven non-infected control mice were euthanized by exposure to CO₂ at 10 and 40 days post infection. The spleen of each animal was removed, and spleen cells (primarily lymphocytes) were harvested by flushing the spleens four times with 3 mL of complete RPMI 1640 medium (RPMI medium with 10% fetal calf serum, 50 uM β-mercaptoethanol), followed by passing the spleen remnant through a 70 μm nylon screen. Cells were washed three times with complete RPMI medium and once with Hank's balanced salt solution, followed by lysis of erythrocytes with hypotonic buffer. The enriched lymphocytes were pelleted by centrifugation at 3000×g, washed with complete RPMI medium, and the final pellet of cells suspended in complete RPMI medium at 2.5×10⁶ cells per mL.

Interferon-γ Secretion Assay

Cells harvested from infected and non infected mice were plated at a density of 2×10⁵ cells per well in 96 well plates and individual 2-D LPE fractions (2 μg protein) were added to the cells in triplicate. After four days of incubation at 37° C. and 5% CO₂, the supernatants from these cultures were assayed for the presence of IFNγ by plate ELISA using the IFNγ kit from Genzyme Diagnostics (Cambridge, Mass.). Quantitation of IFNγ was performed by reading the ELISA plates at A405 and plotting the data against a standard curve of IFNγ. The standard error was within 10% of the mean values.

EXAMPLE II 2-D Liquid Phase Electrophoresis of Culture Filtrate and Cytosolic Proteins

To ensure sufficient protein quantities for both immunological analysis and molecular identification, large aliquots of CFPs (500 mg) and cytosolic proteins (250 mg) were used as starting material. Initial experiments demonstrated quantities of cytosolic proteins greater than 150 mg resulted in excessive precipitation during preparative IEF using the Rotofor apparatus. Moreover, increasing the detergent concentration of the IEF buffer did not solve this problem. Therefore, two preparative IEF runs were performed using 100 mg and 150 mg of the cytosolic proteins. A smaller total quantity of cytosolic protein was used in order to minimize the number of fractions that required pooling and to reduce potential distortion of IEF resolution. The 20 fractions collected from each run were analyzed by SDS-PAGE and silver staining, and like fractions were pooled. A similar problem of protein precipitation was not encountered with the highly soluble CFPs, and 500 mg of CFP was fractionated in a single preparative IEF run. The pH range of the fractions was 3.1 to 12.1 for CFPs and 3.9 to 12.3 for the cytosolic proteins. Analysis of both the culture filtrate and cytosolic protein fractions by SDS-PAGE demonstrated considerable overlap in those fractions at the extreme ends of the pH gradient (3.0 to 4.5 and 10.0 to 12.5). This was likely due to poor resolution by the Rotofor at the ends of the pH range, coupled with the large protein loads used. These overlapping fractions were pooled, resulting in 16 and 13 fractions of CFPs and cytosolic proteins, respectively. Efficient separation was achieved over a broad pH range. The protein content of the IEF fractions varied from 2.9 mg to 34.5 mg (CFPs), and 0.2 mg to 6.3 mg (cytosolic proteins), with the highest protein concentrations observed for fractions in the pH range of 3.8 to 5.1 for CFPs and 5.5 to 6.2 for cytosolic proteins. This is consistent with migration of the proteins of these subcellular fractions by 2-D PAGE.

Separation of IEF fractions in the second dimension was achieved by preparative SDS-PAGE. This resolved proteins into narrow molecular mass fractions. Each IEF fraction was applied to preparative 15% SDS-polyacrylamide gels, and after electrophoresis the proteins were recovered by electroelution using the Whole Gel Elutor. For each IEF fraction 30 preparative SDS-PAGE fractions were collected. However, within individual preparative SDS-PAGE runs, those proteins migrating at 14 kDa or less showed significant overlap. This overlap was also observed when the lower molecular weight fractions were resolved on 10-20% tricine gels. Thus, overlapping fractions in this molecular mass range were pooled. The 2-D LPE of the culture filtrate and cytosolic proteins resulted in 335 and 299 fractions, respectively, with each fraction containing 10 to 545 μg of protein.

EXAMPLE III Production of IFNγ in Response to 2-D LPE Fractions

Prior to testing for T cell stimulation the 2-D LPE fractions were filter sterilized, aliquoted and lyophilized. Previously, it had been demonstrated that proteins isolated with the Whole Gel Eluter were relatively free of SDS and were suitable for direct use in T cell assays (Andersen et al., supra). Analysis of lymphocytes from uninfected C57B1/6 mice by microscopy and assessment of cell growth using the Alamar Blue redox reaction (Ahmed, S A et al., J. Immunol. Methods. 1994, 170:211-224) revealed that the SDS concentrations present in these 2-D LPE fractions did not adversely affect the cells, consistent with the findings of others.

To assess T-cell reactivity to the 2-D LPE fractions, proteins were aliquoted (2 μg/well) in triplicate in 96 well plates and incubated for four days with the lymphocytes Mtb infected or uninfected mice, at which time the level of IFNγ present in the culture supernatant was measured. IFNγ production is a primary readout for T-cell activation (Orme et al., 1993, supra). The specific reactivity of T cells to individual Mtb antigens changes over the course of infection (Cooper et al., supra)). Thus, the reactivity of cells harvested at days 10 and 40 post infection was evaluated. The measurement of IFNγ production in T cells from the day 10 post-infected animals revealed that a large number of culture filtrate and cytosol 2-D LPE fractions induced significant levels of IFNγ production (FIGS. 1 and 2). The level of this reactivity was between 0 and 28.7 ng/mL, and 0 and 9.6 ng/mL for the culture filtrate and cytosol fractions, respectively. It should be noted that unfractionated CFPs and cytosolic proteins induced 5.9 and 1.6 ng/mL of IFNγ, respectively, from the same cells. Moreover none of the 2-D LPE fractions induced significant IFNγ production (<207 pg/mL) from the lymphocytes of uninfected mice, demonstrating that the IFNγ responses of T cells from infected mice were antigen specific. We would have expected the whole unfractionated CFP and cytosolic proteins to stimulate an equal or higher IFNγ response than that induced by individual fractions. Given that the strongest IFNγ responses were induced by the lower molecular weight fractions, it is possible the molar concentration of stimulatory antigens in these fractions was greater than in the entire protein pool. It is also possible that an inhibitor (such as LAM) could have lowered the values obtained with these pools. In general, the 2-D LPE fractions of the CFPs stimulated stronger IFN responses than did the cytosolic proteins. For both the culture filtrate and cytosolic protein fractions the strongest IFNγ response was observed with fractions of <30 kDa and with those in the more acidic pI range. This pattern of reactivity was similar to that obtained by Gulle et al. (supra) for proteins of M. bovis BCG separated by 2-D PAGE and subsequently evaluated in a T cell proliferation assay. This observation agreed with previous reports that the most dominant T cell antigens of M. tuberculosis are associated with the lower molecular weight (<30 kDa) CFPs (Boesen et al., supra; Roberts et al., supra).

A number of the 2-D LPE fractions tested with spleen cells taken 40 day post-infection also induced significant IFNγ production (FIGS. 3 and 4). However, the pattern of reactivity was much less complex than that observed using lymphocytes taken day 10 post-infection. Those 2-D LPE fractions that stimulated the strongest T cell response later in the infection were also strong inducers of IFNγ in the day 10 group, and none of the antigen fractions were specific to the day 40 post-infected animals. These data confirm that the T cell reactivity to specific M. tuberculosis antigens changes over the course of the infection and that a select subgroup of proteins has the capacity to sustain a T cell response (Cooper et al., supra). It is likely that responsiveness to a larger number of antigen fractions at day 10 reflects the relative abundance of these antigens within the spleen (or other sites in the immune system) while the bacteria are actively dividing. Once bacterial growth is contained, the supply of antigens becomes limited, thus reducing T cell responses at later time points

EXAMPLE IV Molecular Characterization of Dominant T Cell Immunogens

In total, 37 2-D LPE fractions were found to induce IFNγ responses that were at least three-fold greater than average response to all culture filtrate fractions or cytosol fractions. These more stimulatory fractions were selected for molecular characterization of their proteins. Analysis by 2-D PAGE and silver nitrate staining demonstrated the presence of one to seven proteins in each fraction. Moreover, the occurrence of multiple proteins in a fraction was primarily a consequence of incomplete resolution by preparative IEF.

Multiple strategies were employed for the identification of the M. tuberculosis protein antigens. For fractions containing more than one protein spot, 2-D PAGE was performed and the gels stained with Coomassie Brilliant Blue. Individual protein spots were excised, followed by in gel digestion with trypsin (Hellman et al., supra), and analysis of peptide fragments by LC-MS or LC-MS-MS. In some instances it was not possible to achieve complete separation of multiple protein spots. Thus for these fractions a gel slice containing more than one spot was digested and the identification of the protein mixture was achieved by analysis of the MS-MS data using the SEQUEST software (Ducret et al., Protein Sci. 1998, 1:106-719; McCormack, A L et al., Anal. Chem. 1997, 69:767-77631). Alternatively, for those fractions containing a single protein species an aliquot (˜5 μg) was directly digested with trypsin and analyzed. The data from protein digests analyzed by LC-MS was searched against the M. tuberculosis proteome database using the MS Fit program (Baker et al., supra), and protein identification was accomplished by matching the experimental molecular mass (m/z) of 3 to 15 peptides to the mass of predicted tryptic fragments of M. tuberculosis proteins. The proteins are listed in Tables 1 and 2, above. Previous studies demonstrated that proteins are accurately identified using as few as 3-4 experimentally determined peptide masses (Pappin, D J et al., Curr. Biol. 1993, 3:327-332). The validity of protein identification was dictated by the MOWSE score assigned by the MS Fit program. All proteins identified by MS Fit in this study had a MOWSE score greater than 1×10³.

When LC-MS-MS data was collected for digests of individual proteins or protein mixtures the data was searched against the M. tuberculosis proteome database using the SEQUEST software. Identification of proteins by this method was often achieved with MS-MS data from only a few (1 to 6) peptides. The Xcorr and ΔCn values assigned by SEQUEST determined the reliability of the MS-MS data for each peptide and the accompanying protein identification. The Xcorr is the raw correlation score, and is directly related to the number of fragment ions match (Ducret, A. et al., supra), whereas the ΔCn is the difference in the correlation score of the top two candidate proteins. When the difference ΔCn between the first and second ranked peptides is greater than 0.1, the first sequence is considered to be accurate with high probability (Eng et al., supra). All peptides assigned to a specific M. tuberculosis gene product based on the experimentally derived MS-MS fragmentation pattern yielded ΔCn values greater than 0.1, and their Xcorr scores were generally greater than 2. In a small number of instances the MS-MS data of only one peptide was used to determine protein identity of the proteins shown in Tables 1 and 2. (See Tables 1 and 2 of Covert et al., supra for additional detail). In such cases, additional information such as observed molecular weight and pI of the protein, was used with the Xcorr and ΔCn values to conclude the identity of the protein.

In all 16 and 18 proteins were identified in the immunodominant 2-D LPE fractions of the culture filtrate and cytosol, respectively (Tables 1 and 2). Several of the proteins identified (ModD, PhoS1, GroES, GroEL2, MPT 64, ESAT6, and FbpA, B and C2) have been shown by others to serve as T cell antigens (Thole, J et al., In: Ratledge, C et al., (eds), Mycobacteria Molecular Biology and Virulence. Blackwell Science, Oxford, UK 1999, pp. 356-370), though not in vivo boosting molecules for use in BCG-vaccinated subjects.

Two proteins (Rv1932 and Rv1827) elucidated herein were recently revealed to be T cell antigens by a similar strategy (Weldingh et al., supra). Many of the identified proteins were found in more than one immunodominant 2-D LPE fraction. This was particularly true for the cytosol fractions where IEF separation was more complex. Multiple fractions containing the same antigen were generally adjacent to each other. The exception to this was where GroEL2 was found in a high molecular weight fraction (D-30) and low molecular weight fractions (D-12, E-11 and E-13) (Table 2 of Covert et al.). The lower molecular weight fractions were hypothesized to possess break down products of GroEL2. Additionally, some proteins identified in the culture filtrate fractions were also found in immunodominant cytosol fractions. While a more thorough separation of proteins may have been desirable, the repeated identification of a small number of well-known and unknown antigens enhanced the level of confidence in this methodology. Equally exciting was the fact that this approach identified a large number of proteins not previously known to be T cell antigens, particularly in the cytosol. While the majority of the novel T cell antigens were assigned to open reading frames of unknown function, some, such as AhpC2, RplL, FixA, and FixB have functions predicted by sequence homology (Cole et al., supra). The FixA and FixB proteins are proposed to participate in β-oxidation of fatty acids, and AhpC2 a putative alkylhydroperoxidase may possess antioxidant activity that contributes to intracellular survival of the bacillus. Of note is RplL (Rv0652), a putative 50S ribosomal protein. The Brucella melitensis homologue of this protein has been shown to be a major antigen that induces delayed type hypersensitivity and is useful in diagnosing brucellosis (Bachrach, G et al., Infect. Immun. 1994, 62:5361-5366). However, the T cell reactivity of the B. melitensis RplL homologue is dependent on post-translational modification of the protein. While it is not known whether M. tuberculosis RplL possesses a similar modification, other proteins of M. tuberculosis are known to be glycosylated (Dobos et al., supra) and this type of modification has been demonstrated to effect T cell reactivity (Horn, C et al., J. Biol. Chem. 1999, 274: 32023-23030). Unlike high throughput recombinant methodologies, a proteomics approach with native molecules will detect antigen reactivity that is dependent on the post-translational modification of the protein. Of the 30 individual proteins identified in this study, 17 of them (Rv0057, Rv3841, Rv1352, Rv1810, Rv3044, Rv0054, Rv0652, Rv3029c, Rv3028Rv2428, Rv2626c, Rv1211, Rv1240, Rv1626, Rv0733, Rv2461c, and Rv0952) represent a pool of new T cell immunogens of M. tuberculosis that induce increased resistance to infection in a subject previously immunized with BCG (as exemplified with Ag85A (=Rv3804c) below). Mycobacterial lipids or lipoglycans may have also contributed to the IFNγ response for some of these novel proteins. However, most of these lipid molecules migrate over a broad acidic pH range (pH 4 to 6), and not all fractions in this range gave high IFNγ responses. Additionally, lymphocytes from uninfected animals did not respond to any of the protein fractions whereas most lipid molecules stimulate innate and non-specific immune responses. This suggests that the IFNγ responses were manifestations of an acquired immune response to a protein or proteins within the 2-D LPE fractions and were not responses to non-protein contaminants. Use of recombinant, cloned proteins (as disclosed herein) and further immunological characterization will increase our understanding of these proteins as vaccine compositions (or skin test antigens for diagnosis).

EXAMPLE V Ag85A (Rv3804c Product) Induces Resistance to Infection by Virulent M. tuberculosis

The protection conferred against an aerosol challenge infection by virulent M. tuberculosis in mice of increasing age is shown in FIG. 5. Mice had been vaccinated with BCG at 6-8 weeks of age and were challenged at various ages thereafter.

In mice 3 and 12 months of age a 10-fold reduction in bacterial load in the lungs was consistently observed thirty days after challenge.

C57B1/6 mice typically live for an average of 22-24 months. In their second year of life this resistance gradually wanes, dropping to 0.7 logs at 16 months, and to 0.35 logs at 20 months of age. As shown in FIG. 6, resistance in the lungs of previously unvaccinated elderly mice was increased by treatment with mycobacterial culture filtrate protein (CFP)-based subunit vaccine (A. D. Roberts, et al., Immunology 85:502-8 (1995)), but the improvement was only marginal.

Because the fact that the majority of T cells that are involved in protection in the lungs of young mice recognize the Ag85 proteins (Cooper et al., supra), the present inventors conceived that this antigen would restimulate existing immunological memory in BCG-vaccinated subjects. To achieve this, native Ag85A was purified as previously described (Belisle et al., supra) and shown to be pure by gel electrophoresis (FIG. 7).

As shown in FIG. 8, mice vaccinated at 3 months of age and then challenged by an aerosol containing M. tuberculosis organisms at 20 months of age were marginally protected (0.47 log) as was anticipated. Boosting with the CFP vaccine (a protein mixture of which approximately 10% consists of the Ag85 complex) had no effect on the subsequent bacterial resistance. However, boosting with purified Ag85A resulted in a 10-fold (1 log) reduction in lung bacterial counts (p<0.001).

Histologic examination of the infected lungs of these animals revealed a further unexpected benefit of the boosting vaccination. In both BCG control and BCG/Ag85 boosted mice the gradual development of a lymphocytic granulomatous response proceeded as expected (FIG. 9). However, careful examination of lesions revealed numerous small foci or pockets of neutrophils distributed throughout the lesions in the BCG control animals.

In contrast, lungs of the Ag85A-boosted mice were mostly devoid of these lesions with only an occasional (usually solitary) neutrophil detected.

These results suggested that not only can mid-life boosting vaccination restore specific antimicrobial resistance in elderly mice to levels expressed by young BCG-vaccinated animals, but lung tissue damage and degeneration, which is almost certainly the basis of the influx of neutrophils into the lesions of the old mice, was also dramatically reduced.

The references cited above are all incorporated by reference herein, whether specifically incorporated or not.

Having now fully described this invention, it will be appreciated by those skilled in the art that the same can be performed within a wide range of equivalent parameters, concentrations, and conditions without departing from the spirit and scope of the invention and without undue experimentation. 

1. A method for boosting the immune response to Mycobacterium tuberculosis (Mtb) in a mammal which has been vaccinated neonatally or early in life with BCG, to increase the resistance of said mammal to Mtb infection, said method comprising: administering to a mammal in need of said boosting, an immunogenically effective amount of an Mtb immunogenic protein composition that comprises one or more purified Mtb proteins or homologues of said proteins, which protein or homologue is characterized in that it: (a) stimulates significant interferon-γ secretion by T lymphocytes of a mammal which has been immunized with Mtb antigens; and/or (b) when administered to a mammalian subject at an age when immunity induced by said BCG vaccination is waning, significantly increases the resistance of said subject to Mtb infection, thereby increasing the resistance of said mammal to Mtb infection.
 2. The method of claim 1 wherein said mammal is a human.
 3. The method of claim 2 wherein the administering is performed between about 1 year and about 10 years after the BCG vaccination.
 4. The method of claim 2 wherein the administering is performed when said human is at least about 10 years of age.
 5. The method of claim 4 wherein the administering is performed when said human is at least about 15 years of age.
 6. The method of claim 5 wherein said administering is performed when said human is at least about 20 years of age.
 7. The method of claim 1 wherein the immunogenic protein composition comprises one or more of said purified Mtb proteins selected from the group consisting of the product of the Mtb gene Rv3804c, Rv1886c, Rv0129c, Rv1860, Rv0934, Rv0577, Rv1827, Rv3841, Rv1932, Rv1352, Rv3418c, Rv3875, Rv1810, Rv1980c, Rv0350, Rv3044, Rv0054, Rv0652, Rv3029c, Rv3028c, Rv2428, Rv0440Rv2031c, Rv2626c, Rv1211, Rv1240, Rv1626, Rv0733, Rv2461c, and Rv0952.
 8. The method of claim 1 wherein the immunogenic protein composition comprises one or more of said purified Mtb proteins selected from the group consisting of SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO:10, SEQ ID NO:11, SEQ ID NO:12, SEQ ID NO:13, SEQ ID NO:14, SEQ ID NO:15, SEQ ID NO:16, SEQ ID NO:17, SEQ ID NO:18, SEQ ID NO:19, SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, SEQ ID NO:24, SEQ ID NO:25, SEQ ID NO:26, SEQ ID NO:27, SEQ ID NO:28, SEQ ID NO:29, SEQ ID NO:30 and SEQ ID NO:31, wherein, when said protein is an Mtb secreted protein, the sequence is the truncated sequence of the above sequences from which the signal sequence has been removed.
 9. The method of claim 8, wherein the proteins are selected from the group consisting of SEQ ID NO:6; SEQ ID NO:8; SEQ ID NO:10; SEQ ID NO:13; SEQ ID NO:16; SEQ ID NO:17; SEQ ID NO:18; SEQ ID NO:19; SEQ ID NO:20; SEQ ID NO:21; SEQ ID NO:24; SEQ ID NO:25; SEQ ID NO:26; SEQ ID NO:27; SEQ ID NO:28;SEQ ID NO:29 and SEQ ID NO:30.
 10. The method of claim 9, wherein the proteins are selected from the group consisting of SEQ ID NO:6; SEQ ID NO:7; SEQ ID NO:10; SEQ ID NO:13; SEQ ID NO:24; SEQ ID NO:25 and SEQ ID NO:27.
 11. The method of claim 7 wherein the immunogenic protein composition further includes Ag85A (SEQ ID NO:31).
 12. The method of claim 7 wherein the immunogenic protein composition is a single Mtb protein.
 13. The method of claim 12 wherein the single protein is Ag85A (SEQ ID NO:31).
 14. The method of claim 1 wherein the immunogenic composition further comprises an adjuvant or an immunostimulatory protein different from said immunogenic Mtb protein.
 15. The method of claim 14 wherein said immunostimulatory protein is a cytokine.
 16. The method of claim 15 wherein said cytokine is interleukin 2 or GM-CSF.
 17. The method of claim 14, wherein said adjuvant is selected from the group consisting of (a) ISAF-1 (5% squalene, 2.5% pluronic L121, 0.2% Tween 80) in phosphate-buffered solution with 0.4 mg of threonyl-muramyl dipeptide; (b) de-oiled lecithin dissolved in an oil; (c) aluminum hydroxide gel; (d) a mixture of (b) and (c) (e) QS-21; and (f) monophosphoryl lipid A adjuvant.
 18. The method of claim 17 wherein the adjuvant is monophosphoryl lipid A adjuvant solubilized in 0.02% triethanolamine.
 19. The method of claim 17 wherein said composition further comprises recombinant interleukin-2.
 20. An immunogenic composition useful for boosting the immune response to Mtb in a mammal which has been vaccinated neonatally or early in life with BCG, to increase the resistance of said mammal to Mtb infection compared to the resistance of a mammal to BCG vaccination, said composition comprising one or more purified Mtb proteins selected from the group consisting of: (a) the product of the Mtb gene Rv1352, (b) the product of the Mtb gene Rv1810, (c) the product of the Mtb gene Rv3044, (d) the product of the Mtb gene Rv0054, (e) the product of the Mtb gene Rv3028c, (f) the product of the Mtb gene Rv2626c, (g) the product of the Mtb gene Rv1240, (h) the product of the Mtb gene Rv1626, (i) the product of the Mtb gene Rv0733, (j) the product of the Mtb gene Rv2461c, (k) the product of the Mtb gene Rv0952, (l) the product of the Mtb gene Rv3418c, (m) the product of the Mtb gene Rv0350, and (n) a homologue of any one of proteins (a)-(k).
 21. An immunogenic composition comprising two or more of the following purified Mtb proteins or homologues: (i) the purified Mtb proteins or homologues of the composition of claim 20, (ii) a purified Mtb protein product of the Mtb gene Rv1860, Rv0934, Rv3875, Rv2428, Rv0440, Rv2031c or Rv1211.
 22. An immunogenic composition comprising three or more of said purified Mtb proteins or said homologues of the composition of claim
 21. 23. The composition of claim 20 wherein the one or more purified proteins (a) comprises a sequence selected from the group consisting of SEQ ID NO: 10, SEQ ID NO:13, SEQ ID NO:16, SEQ ID NO:17, SEQ ID NO:20, SEQ ID NO:24, SEQ ID NO:26, SEQ ID NO:27, SEQ ID NO:28, SEQ ID NO:29, and SEQ ID NO:30; or (b) consists of a sequence SEQ ID NO:11 or SEQ ID NO:15, and wherein, when said protein is an Mtb secreted protein, the sequence is a truncated sequence of the above sequences from which the signal sequence has been removed.
 24. The composition of claim 23 wherein the one or more proteins has a sequence selected from the group consisting of SEQ ID NO:10; SEQ ID NO:13; SEQ ID NO:24; SEQ ID NO:25 and SEQ ID NO:27.
 25. The composition of claim 20 which further includes Ag85A (SEQ ID NO:31).
 26. An immunogenic composition that comprises (a) a purified Mtb protein or homologue according to claim 20, (b) a product of the Mtb gene Rv0934, Rv2428, Rv0440, Rv2031c, orRv1211, or of a homologue of said Mtb gene Rv0934, Rv2428, Rv0440, Rv2031c, or Rv1211, and further comprises an immunostimulatory protein different from said Mtb proteins.
 27. The composition of claim 26 wherein said immunostimulatory protein is a cytokine.
 28. The composition of claim 27 wherein said cytokine is interleukin 2 or GM-CSF.
 29. The composition of claim 27 wherein said adjuvant is selected from the group consisting of: (a) ISAF-1 (5% squalene, 2.5% pluronic L121, 0.2% Tween 80) in phosphate-buffered solution with 0.4 mg of threonyl-muramyl dipeptide; (b) de-oiled lecithin dissolved in an oil; (c) aluminum hydroxide gel; (d) a mixture of (b) and (c) (e) QS-21; and (f) monophosphoryl lipid A adjuvant.
 30. The composition of claim 29 wherein the adjuvant is monophosphoryl lipid A adjuvant solubilized in 0.02% triethanolamine.
 31. The composition of claim 29 that further comprises recombinant interleukin-2.
 32. The composition of claim 21, wherein the two or more purified Mtb proteins are selected from the group consisting of the product of the following Mtb genes: Rv1352, Rv3418c, Rv1810, Rv0350, Rv3044, Rv0054, Rv3028c, Rv2626c, Rv1240, Rv1626, Rv0733, Rv2461c, and Rv0952.
 33. The composition of claim 22, wherein the three or more purified Mtb proteins are selected from the group consisting of the product of the Mtb gene: Rv1352, Rv3418c, Rv3875, Rv1810, Rv0350, Rv3044, Rv0054, Rv3028c, Rv2626c, Rv1240, Rv1626, Rv0733, Rv2461c, and Rv0952.
 34. The composition of claim 21 wherein the two or more purified proteins have a sequence selected from the group consisting of SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:7, SEQ ID NO:10, SEQ ID NO:11, SEQ ID NO:12, SEQ ID NO:13, SEQ ID NO:15, SEQ ID NO:16, SEQ ID NO:17, SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, SEQ ID NO:24, SEQ ID NO:25, SEQ ID NO:26, SEQ ID NO:27, SEQ ID NO:28, SEQ ID NO:29, and SEQ ID NO:30, wherein, when said protein is an Mtb secreted protein, the sequence is a truncated sequence of the above sequences from which the signal sequence has been removed.
 35. The composition of claim 22 wherein the three or more purified proteins have a sequence selected from the group consisting of SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:7, SEQ ID NO:10, SEQ ID NO:11, SEQ ID NO:12, SEQ ID NO:13, SEQ ID NO:15, SEQ ID NO:16, SEQ ID NO:17, SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, SEQ ID NO:24, SEQ ID NO:25, SEQ ID NO:26, SEQ ID NO:27, SEQ ID NO:28, SEQ ID NO:29, and SEQ ID NO:30, wherein, when said protein is an Mtb secreted protein, the sequence is a truncated sequence of the above sequences from which the signal sequence has been removed.
 36. The composition of claim 23 that further comprises (i) an adjuvant or (ii) an immunostimulatory protein that is not an Mtb protein.
 37. An immunogenic composition that comprises a purified Mtb protein or homologue of the composition of claim 20, a product of the Mtb gene Rv1860, Rv0934, Rv0440, Rv2031c, or Rv1211, or a product of a homologue of said Mtb genes and further comprises an adjuvant.
 38. The composition of claim 34 which further comprises SEQ ID NO:31.
 39. The composition of claim 35 which further comprises SEQ ID NO:31. 